In an oil-cooled screw compressor, a tooth crest arc of a fixed width is provided to the tooth crest of a male tooth profile, and simultaneously a tooth bottom arc is provided to the tooth bottom of a female tooth profile. Due to the actions thereof, the operation chamber immediately before disappearing exists only in a bottom half region from a line that connects the centers of the male and female tooth profiles, and the opening area relative to the volume of the operation chamber can be increased. As a result, the discharge of oil becomes smooth and energy loss is reduced.