To reduce noise generated during operation of a drain pump installed to an air conditioner.

In this drain pump 1a, a rotary blade 60 is arranged inside a pump chamber 14 of a pump main body 10, and a cover member 120 is provided with an opening part 122 having a central part through which a shaft part 61 of the rotary blade 60 penetrates, The lower face 130 of the cover member 120 opposing to the upper face 60a of the rotary blade 60 is formed to be an inclined face to the direction separating from the upper face 60a of the rotary blade 60 from the inner peripheral part toward the outer peripheral part. A thickness dimension between the upper face 124 and the lower face 130 of the cover member 120 is formed to have a tapered shape gradually thinning from the inner peripheral part toward the outer peripheral part. Even if the inclined face has uniform thickness and is inclined to the direction gradually separating from the upper face 60a of the rotary blade 60 toward the outer peripheral part, effects are not changed.