Idol I

Director

• 
  Lee Gwang Young

Music Director

• 
  Park Se Jun

Screenwriter

• 
  Kim Da Rin

Main Role

• 
  Choi Soo Young

  Maeng Se Na

  Main Role
• 
  Kim Jae Yeong

  Do Ra Ik / Laik

  Main Role
• 
  Jung Jae Kwang

  Kwak Byeong Gyun

  Main Role
• 
  Choi Hee Jin

  Hong Hye Ju

  Main Role
• 
  Kim Hyun Jin

  Park Chung Jae

  Main Role

Support Role

• 
  Kim Won Hae

  Cheon Gwang Su [Se Na’s boss]

  Support Role
• 
  Jung Man Sik

  Geum Bo Sang [Goldi Entertainment CEO]

  Support Role
• 
  Ahn Woo Yeon

  Kang U Seong [Gold Boys leader]

  Support Role
• 
  Park Jeong Woo

  Choi Jae Hui [Gold Boys drummer]

  Support Role
• 
  Choi Geon

  Lee Yeong Bin [Gold Boys keyboardist]

  Support Role
• 
  Kim Min Sang

  Kwak Jong Cheol [Byeong Gyeon's father]

  Support Role
• 
  Woo Mi Hwa

  Do Mi Gyeong [Ra Ik's mother]

  Support Role
• 
  Jo Hyun Sik

  Jang Han Gu [Ra Ik's manager]

  Support Role
• 
  Nam Joong Gyu

  [Manager Jang's assistant]

  Support Role
• 
  Jo Jae Ryong

  Yoo Nam Sik [Detective team leader]

  Support Role
• 
  Jo Wan Ki

  Kim Gi Uk [Prosecutor]

  Support Role
• 
  Oh Gi Gwang

  [Youngest detective]

  Support Role
• 
  Ha Ju Ae

  [Ra Ik's stalker]

  Support Role

Guest Role

• 
  Cha Yu Jin

  Kim Min Ji [Ra Ik's doctor] (Ep. 1)

  Guest Role
• 
  Kim Mi Hwa

  Seo Hyeon Suk [Ra Ik's housekeeper] (Ep. 1)

  Guest Role
• 
  Park Yong

  [Judge] (Ep. 1)

  Guest Role
• 
  Ahn Jung Ho

  [Reporter] (Ep. 1)

  Guest Role
• 
  Choi Yeon Hwa

  [Reporter] (Ep. 1)

  Guest Role
• 
  Hong Dal Pyo

  [Protestor] (Ep. 1)

  Guest Role
• 
  Nam Jin Bok

  [Inspector] (Ep. 1)

  Guest Role
• 
  Ha Seung Yeon

  [Goldi staff] (Ep. 1)

  Guest Role
• 
  Sung Ryung

  [Ra Ik's stalker] (Ep. 1)

  Guest Role
• 
  Han Se Jin

  [Music show MC] (Ep. 1)

  Guest Role
• 
  Lee Seung Hun

  [Chief prosecutor] (Ep. 1)

  Guest Role
• 
  Park Won Sang

  Maeng Ji Yong [Se Na's father] (Ep. 2)

  Guest Role
• 
  Lee Yoon Sang

  [Judge] (Ep. 2)

  Guest Role
• 
  Choi Won

  [Public defender] (Ep. 2)

  Guest Role
• 
  Kim Hee Sung

  Do Ra Ik [Child] (Ep. 3)

  Guest Role
• 
  Hwang Dong Ha

  [Police officer] (Ep. 3)

  Guest Role
• 
  Yang Heung Joo

  [NFS examiner] (Ep. 3)

  Guest Role
• 
  Park Jeong Seo

  [Mechanic] (Ep. 5)

  Guest Role
• 
  Kim Jin Seo

  [Police officer] (Ep. 7)

  Guest Role
• 
  Min Sang Chul

  [Doctor] (Ep. 8)

  Guest Role
• 
  Lee Ki Sub

  [Prosecutor] (Ep. 8)

  Guest Role
• 
  Kwon Ban Suk

  [Prosecutor] (Ep. 8)

  Guest Role
• 
  Shin Min Soo

  [Security guard] (Ep. 8)

  Guest Role
• 
  Kim Geon Ho

  [Hotel employee] (Ep. 8)

  Guest Role
• 
  Kim Jong Gu

  [Restaurant owner] (Ep. 9)

  Guest Role
• 
  Jung Kyu Soo

  [Mountain cabin owner] (Ep. 10)

  Guest Role
• 
  Seo Kwang Jae

  [Doctor] (Ep. 11)

  Guest Role
• 
  Shim Yoon Bo

  Reporter Baek

  Guest Role
• 
  Park Sharon

  Maeng Se Na [Teen]

  Guest Role
• 
  Jeon Gook Hwan

  Chairman Hong [Hye Ju's father]

  Guest Role
• 
  Jung Hwan

  Manager Lee [Se Na's colleague]

  Guest Role
• 
  Kim Jae Il

  [Detective]

  Guest Role
• 
  Kim Kye Hyung

  [Detective]

  Guest Role
• 
  Lee Joo Hyung

  [Investigator]

  Guest Role
• 
  Kwon Chae Won

  [Music show MC]

  Guest Role
• 
  Kim Shi Heon

  [Gwang Su's lawyer team]

  Guest Role
• 
  Kwak Dae Hee

  [Arch Entertainment executive]

  Guest Role
• 
  Heo Jun Seo

  Do Ra Ik [Young]

  Guest Role
• 
  Kim Hye Jun Guest Role