The movie is based on the real events of the "Na-young Case" that took place in December 2008 in which an eight-year-old girl (alias Na-young) was on her way to school when she was kidnapped by 57-year-old Cho Doo Soon (Jo Du Sun), who was drunk at the time. Cho raped and beat Nayoung at a public squat toilet. Na-young had injures to her internal organs, and was taken to a hospital, surviving the incident. Cho was arrested and eventually sentenced to 12 years in prison. The case sparked outrage and protest including Nayoung's parents and many others.
Director Lee Joon-ik had retired briefly from the local film industry following the lackluster commercial performance of his previous effort Krieg der Königreiche (2011). He returned two years later with So-won (2013), casting top actor Sul Kyung-gu in one of the lead roles. Lee said he wanted to "make a happy movie that begins with a tragedy. With this heartbreaking material, I wanted to make the film as happy as possible. I am going to present a human drama where hope blooms at the edge of unhappiness and desperation, after a series of ordeals and hardships." He maintained that he made the film to "encourage Na-young and other victims of sex crimes," and that instead of other films with a similar subject matter that focus on sensationalist aspects, like the crime itself, So-won (2013) is about "what happens after, and is more about showing how life is good and worth living, emphasizing how the community rallied around the victim."
Actress Uhm Ji-won had previously declined the film two years before, thinking she wasn't talented enough or ready to take on the intense emotions her role (as So-won's mother) required. But when Sol's wife and her close friend Song Yun-ah sent the script to her, Uhm said, "I started to think that this movie was supposed to come to me. I felt that someone should tell this valuable story. And I gained the courage to think that I could try it.
Shooting began in Changwon on April 13, 2013. Throughout the filming, Sul Kyung-gu stayed in character as So-won's father, wearing his character's clothes all the time. The film wrapped on June 24, 2013 in Busan; the entire cast attended the final day of filming.
This film is in the Official Top 250 Narrative Feature Films on Letterboxd.