The present invention relates to a pharmaceutical composition comprising dutasteride and propylene glycol monolaurate, which improves the stability of dutasteride, which is a poorly soluble drug as a 5-alpha reductase inhibitor, and a process for its preparation. More particularly, the present invention also relates to a capsule formulation which is smaller in size than a commercial dutasteride capsule formulation (AVODART?, but has the equivalent dissolution rate by preparing a pharmaceutical composition comprising propylene glycol monolaurate and dutasteride, which can improve the stability of the dutasteride. A dutasteride formulation having enhanced patient' s compliance and improved stability and a method for producing the same are provided.