Ji Jin Hee (Ji Jin Hui) as Cho Jae Hee who despite his indifferent attitude creates great architectural designs. He has no interest in women and marriage but his life changes when he meets two different women and a dog.
Uhm Jung Hwa as Jang Moon Jung, a doctor who is tired of going to blind dates that her father arrange for her for fear that she would not get married. Her first encounter with Cho Jae Hee leads to an exciting chapter of her life.
Kim So Eun as Jung Yoo Jin who lives next door to Cho Jae Hee. They don't get along at first but everything starts to change after Yoo Jin brings Jae Hee to the hospital where Doctor Jang works. She has a dog named Sangu.
Yoo Ah In as Park Hyun Kyu who works in the office of Cho Jae Hee. He is interested in Jung Yoo Jin.
Yang Jung Ah as Yoon Ki Ran, a friend and colleague of Cho Jae Hee. She always fixes the mess that Architect Cho makes to avoid losing clients and workers.