A screw compressor includes a casing, a screw rotor disposed in a cylinder portion of the casing to define a compression chamber, and a capacity control slide valve. Fluid sucked into the compression chamber is compressed by rotation of the screw rotor. The slide valve is slidable along a rotation axis of the screw rotor and is opposed to an outer circumferential surface of the screw rotor. The slide valve includes a dynamic pressure generator formed on an opposed surface of the slide valve that is opposed to the screw rotor to generate a dynamic pressure using fluid in contact with the opposed surface of the slide valve. The slide valve is configured so that the dynamic pressure generated by the dynamic pressure generator avoids contact between the slide valve and the screw rotor.