A spool valve includes: a cylindrical tubular sleeve that extends in an axial direction and comprises a first port and a second port separated from each other in the axial direction, and a cylindrical columnar spool that extends in the axial direction and comprises a diameter reduced portion. The cylindrical columnar spool moves in the axial direction through the sleeve and opens and closes the first port to cause the first port to or not to communicate with the second port, and the first port has a first through hole having a first width in a circumferential direction of the sleeve, and a second through hole having a second width different from the first width in the circumferential direction.