A Hard Day

Assistant Editor

• 
  Im Hye Jin
• 
  Kim U Hyeon

Composer

• 
  Mok Young Jin

Editor

• 
  Kim Chang Ju

Executive Producer

• 
  Jang Won Seok

Screenwriter

• 
  Lee Hae Joon

Screenwriter & Director

• 
  Kim Sung Hoon

Visual Effects

• 
  Jung Do An
• 
  Cheon Rae Hun

Main Role

• 
  Lee Sun Kyun

  Ko Geon Soo

  Main Role
• 
  Jo Jin Woong

  Park Chang Min

  Main Role

Support Role

• 
  Joo Seok Tae

  Detective Nam

  Support Role
• 
  Lee Jae Won

  Jo Neung Hyun

  Support Role
• 
  Shin Jung Keun

  [Detective Squad Chief]

  Support Role
• 
  Jung Man Sik

  Choi Sang Ho [Detective]

  Support Role
• 
  Shin Dong Mi

  Go Hee Young [Geon Soo's younger sister]

  Support Role
• 
  Heo Jung Eun

  Go Min Ah [Geon Soo's daughter]

  Support Role
• 
  Kim Dong Young

  Do Hee Cheol [Detective]

  Support Role
• 
  Park Bo Gum

  Lee Jin Ho [Officer investigating hit and run]

  Support Role

Guest Role

• 
  Ki Ju Bong

  Director Kim

  Guest Role
• 
  Kim Kang Hyun

  Yeong Cheol [Geon Soo's brother-in-law]

  Guest Role
• 
  Kim Bo Kyung

  [Ex-wife]

  Guest Role
• 
  Nam Kyung Eup

  [High ranking police officer]

  Guest Role
• 
  Kim Hae Gon

  [Pig safe owner]

  Guest Role
• 
  Song Young Gyu

  [Inspection team leader]

  Guest Role
• 
  Lee Ji Hoon

  Hwang Jae Seong [Police officer in weapons/chemical storage room]

  Guest Role

Bit part

• 
  Jo Ha Seok

  Lee Gwang Min

  Bit part
• 
  Jang Nam Boo

  President Choi

  Bit part
• 
  Jang Yoo

  [Funeral Home director]

  Bit part
• 
  Jung Woo Hyuk

  [Funeral home security guard]

  Bit part
• 
  Kim Jung Woo

  [Funeral hall police officer]

  Bit part
• 
  Kim Geon Ho

  [Mutual aid company company employee]

  Bit part
• 
  Kim Kyung Bum

  [Drunk senior police officer]

  Bit part
• 
  Jang In Sub

  Lee Dong Yoon [Police on drunk crackdown

  Bit part
• 
  Bae Yoo Ram

  [Drinking Control resident registration]

  Bit part
• 
  Kim Seung Hoon

  [Chang Min's taxi driver]

  Bit part
• 
  Seo Hyeon Woo

  [Ohamma inspection team member]

  Bit part
• 
  Lee Hee Suk

  [Cabinet inspection team member]

  Bit part
• 
  Yoo Soon Woong

  [Traffic manager]

  Bit part
• 
  Kim Geu Lim

  [Traffic police officer]

  Bit part
• 
  Lee Shi Heon

  [Interrogation room secretary]

  Bit part
• 
  Lee Joon Hyuk

  [Quarrelsome truck man]

  Bit part
• 
  Lee Hyun Kul

  [Big guy in a truck]

  Bit part
• 
  Lee Seung Jun

  [Detective conducting bomb demonstration]

  Bit part
• 
  Ahn Soo Ho

  [Funeral limousine driver]

  Bit part
• 
  Lee Geun Hoo

  [Mechanic]

  Bit part
• 
  Baek Jong Hwan

  [Employee on the roof of pig safe]

  Bit part
• 
  Choi Eun Suk

  [Bomb expert, holds demonstration]

  Bit part