Song Kang-ho as Sang-hyun

Gang Dong-won as Dong-soo

Bae Doona as Su-jin

IU as So-young

Lee Joo-young as Detective Lee

Lim Seung-soo as Hae-jin

Park Ji-yong as Woo-sung

Song Sae-byuk as Orphanage Director

Kim Sun-young as Orphanage Director's wife

Lee Mu-saeng as Seon-ho

Lee Dong-hwi as Mr. Song

Kim Sae-byuk as Song's Wife

Bek Hyun-jin as Detective Choi

Oh Hee-jun as Choi's Subordinate

Ryu Kyung-soo as Tae-ho

Jong Ho as Young-gil

Seong Yu-bin as Young-min

Park Kang-seop as Si-woo

Kim Keum-soon as Ms. Park

Kang Gil-woo as Mr. Im

Kim Yae-eun as Im's Wife

Park Hae-jun as Mr. Yoon

Jung Ji-woo as Yoon's Wife

Ryu Ji-an as Yun-ah

Yun Seul as Babybox Staff 1

Jang Hye-min as Babybox Staff 2

Jeong Jong-yeol as Babybox Pastor

Jung Ah-young as Jung-ae

Lee Ye-seo as Ye-seo

Choi Hee-jin as Mi-sook

Lee Do-goon as Police Officer

Kim Do-yeon as Seon-ah

Choi Hyo-sang as Doctor

Kang Min-ji as Nurse 1

Lee Ga-kyung as Nurse 2

Yang Gwon-seok as Taxi Driver

Lee Doo-seok as Gyu-seok

Yoon Sang-hak as Granny in front of the Laundromat

Lee Do-gyoo as 4-Year-Old Woo-sung

Lee Yoo-joo as Little Girl at So-young's House 1

Kang Gyoo-rin as Little Girl at So-young's House 2

Kim Joo-eun as Little Girl at So-young's House 3

Lim Ga-Young as 19-Years-Old Girl at So-young's House

Woo Sung-min as Orphanage Kid 1

Choi Yoon-woo as Orphanage Kid 2

Jung Hyuk as Teenager 1

Lee Dong-hyeon as Teenager 2

Kim Yoon-ho as Teenager 3

Kim Do-yeop as Teenager 4

Song Ji-ho as Teenager 5

Kim Soo-ji as Teenager 6

Park Jong-hyeon as Detective 1

Jeon Sun-ho as Ji-yeong

Park Yeong-joon as Orphanage Staff

Hwang Do-yoon as Babybox Baby 1

Kim Da-na as Babybox Baby 2

Kim Soo-hyeon as Babybox Baby 3

Bae Ga-jin as Babybox Nanny 1

Kim Jin-ah as Babybox Nanny 2

Son Yeong-ok as Sang-hyun's Mother

Jeong Myeong-yeon as Sang-hyun's Wife

Sin Chae-rin as Young Yun-ah

Park Geon-woo as Young Dong-soo

Choi Gi-sang as First Director of the Orphanage

Park Byeong-gwan as Second Director of the Orphanage

Na Gyeong-cheol as News Anchor (voice)

Lee Ga-eun as Subway Announcement (voice)