The cast of "Whats Wrong with Secretary Kim" includes the following actors and their respective roles:

• Park Seo-joon as Lee Young-joon / Lee Sung-hyun
• Moon Woo-jin as 9-year-old Lee Sung-hyun
• Park Min-young as Kim Mi-so
• Lee Tae-hwan as Lee Sung-yeon
• Kim Byeong-Ok as Chairman Lee
• Kim Hye-Ok as Madame Choi
• Kang Ki-young as Park Yoo-shik
• Hwang Chan-sung as Go Gwi-nam
• Pyo Ye-jin as Kim Ji-ah

Note that the cast list may vary slightly depending on the source.