diff --git a/docs/protocols/alpha.rst b/docs/protocols/alpha.rst
index f9cc0cf8768309025019b6e38ce05c3123fa9938..8174961a0b257d8a131c17250f9f637b81f1ddec 100644
--- a/docs/protocols/alpha.rst
+++ b/docs/protocols/alpha.rst
@@ -51,3 +51,5 @@ Internal
 
 - Fail earlier when a smart rollup commitment is in conflict when cementing.
   (MR :gl:`!8128`)
+
+- split smart rollup origination fct for readibility. (MR :gl:`!8276`)
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_storage.ml b/src/proto_alpha/lib_protocol/sc_rollup_storage.ml
index ef23b9092f14c2e07006ce9001cff3b52c5b39d2..7333f2c6c917951e39faad960fc7dc6b1324e91e 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_storage.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollup_storage.ml
@@ -29,10 +29,12 @@ module Store = Storage.Sc_rollup
 module Commitment = Sc_rollup_commitment_repr
 module Commitment_hash = Commitment.Hash
 
-(** [address_from_nonce ctxt nonce] produces an address completely determined by
-    an operation hash and an origination counter, and accounts for gas spent. *)
-let address_from_nonce ctxt nonce =
+(** [new_address ctxt] produces an address completely
+    determined by an operation hash and an origination counter, and
+    accounts for gas spent. *)
+let new_address ctxt =
   let open Result_syntax in
+  let* ctxt, nonce = Raw_context.increment_origination_nonce ctxt in
   let* ctxt =
     Raw_context.consume_gas ctxt Sc_rollup_costs.Constants.cost_serialize_nonce
   in
@@ -47,26 +49,21 @@ let address_from_nonce ctxt nonce =
       in
       (ctxt, Sc_rollup_repr.Address.hash_bytes [nonce_bytes])
 
-let originate ctxt ~kind ~parameters_ty ~genesis_commitment =
+let init_genesis_info ctxt address genesis_commitment =
   let open Lwt_result_syntax in
-  let*? ctxt, genesis_commitment_hash =
+  let level = (Raw_context.current_level ctxt).level in
+  let*? ctxt, commitment_hash =
     Sc_rollup_commitment_storage.hash ctxt genesis_commitment
   in
-  let*? ctxt, nonce = Raw_context.increment_origination_nonce ctxt in
-  let*? ctxt, address = address_from_nonce ctxt nonce in
-  let* ctxt, pvm_kind_size = Store.PVM_kind.init ctxt address kind in
-  let origination_level = (Raw_context.current_level ctxt).level in
-  let* ctxt, genesis_info_size =
-    Store.Genesis_info.init
-      ctxt
-      address
-      {commitment_hash = genesis_commitment_hash; level = origination_level}
-  in
-  let* ctxt, param_ty_size_diff =
-    Store.Parameters_type.init ctxt address parameters_ty
-  in
-  let* ctxt = Sc_rollup_staker_index_storage.init ctxt address in
-  let* ctxt, lcc_size_diff =
+  let genesis_info = Commitment.{commitment_hash; level} in
+  let* ctxt, size = Store.Genesis_info.init ctxt address genesis_info in
+  return (ctxt, genesis_info, size)
+
+let init_commitment_storage ctxt address
+    ({commitment_hash = genesis_commitment_hash; level = origination_level} :
+      Commitment.genesis_info) genesis_commitment =
+  let open Lwt_result_syntax in
+  let* ctxt, lcc_size =
     Store.Last_cemented_commitment.init ctxt address genesis_commitment_hash
   in
   let* ctxt, commitment_size_diff =
@@ -104,17 +101,38 @@ let originate ctxt ~kind ~parameters_ty ~genesis_commitment =
       origination_level
       [genesis_commitment_hash]
   in
+  return
+    ( ctxt,
+      lcc_size + commitment_size_diff + commitment_added_size_diff
+      + commitment_first_publication_level_diff
+      + commitments_per_inbox_level_diff )
+
+let originate ctxt ~kind ~parameters_ty ~genesis_commitment =
+  let open Lwt_result_syntax in
+  let*? ctxt, address = new_address ctxt in
+  let* ctxt, pvm_kind_size = Store.PVM_kind.init ctxt address kind in
+  let* ctxt, param_ty_size =
+    Store.Parameters_type.init ctxt address parameters_ty
+  in
+  let* ctxt = Sc_rollup_staker_index_storage.init ctxt address in
+  let* ctxt, genesis_info, genesis_info_size_diff =
+    init_genesis_info ctxt address genesis_commitment
+  in
+  let* ctxt, commitment_size_diff =
+    init_commitment_storage ctxt address genesis_info genesis_commitment
+  in
+  (* TODO: https://gitlab.com/tezos/tezos/-/issues/4551
+     There is no need to have both `origination_size` and the size of storage.
+     We should remove one of them. *)
   let addresses_size = 2 * Sc_rollup_repr.Address.size in
   let stored_kind_size = 2 (* because tag_size of kind encoding is 16bits. *) in
   let origination_size = Constants_storage.sc_rollup_origination_size ctxt in
   let size =
     Z.of_int
-      (origination_size + stored_kind_size + addresses_size + lcc_size_diff
-     + commitment_size_diff + commitment_added_size_diff
-     + commitment_first_publication_level_diff + param_ty_size_diff
-     + pvm_kind_size + genesis_info_size + commitments_per_inbox_level_diff)
+      (origination_size + stored_kind_size + addresses_size + param_ty_size
+     + pvm_kind_size + genesis_info_size_diff + commitment_size_diff)
   in
-  return (address, size, genesis_commitment_hash, ctxt)
+  return (address, size, genesis_info.commitment_hash, ctxt)
 
 let kind ctxt address =
   let open Lwt_result_syntax in