Pemeran How to Be Thirty

Jung In Sun

as Seo Ji Won

Pemeran Utama

Kang Min Hyuk

as Lee Seung Yoo

Pemeran Utama

Song Jae Rim

as Cha Do Hun

Pemeran Utama

Cha Min Ji

as Hong Ah Young

Pemeran Utama

Ahn Hee Yeon (안희연)

as Lee Ran Joo

Pemeran Utama

Baek Sung Chul

as Hyung Joon Young

Pemeran Utama

Kim Ji Sung

as Lee Hye Ryeong [Seung Yu's girlfriend]

Pemeran Pembantu

Lee Chae Won

as Yoon Sun Mi [Ji Won's assistant manager]

Pemeran Pembantu

Lee Kang Min

as Kim Byeong Ho [A Yeong's ex-boyfriend] (Ep. 1-3, 6)

Bintang Tamu

Kwon Dong Ho

as [Psycho Bride movie director] (Ep. 3, 6, 13-14)

Bintang Tamu

Ryu Yeon Seok

as [Announcer] (Ep. 6)

Bintang Tamu

Seo Ji Mi

as [Fitness Instructor] (Ep.4,9)

Bintang Tamu

O Ji Yeong

as [Radio Program Staff]

Bintang Tamu

Kim Min

as [Radio program staff]

Bintang Tamu

Kwon Jung Eun

as Seo Ji Won [Teen]

Bintang Tamu

Kwon Yong Wook

as Lee Seung Yoo [Young]

Bintang Tamu

Bae Ha Neul

as [Lee Ran Joo's Date] (Ep.7)

Bintang Tamu

Oh Ki Hwan

Sutradara

Shim Tae Young

as Kim Jin Woo

Bit part

Hong I Hyun

as Park Jin Su (Ep.11)

Bit part