In a miter saw, a dust relief mechanism is provided in side fence portion of a fence on upper side of a base. The dust relief mechanism comprises a first relief groove portion penetrating in left-right direction at a lower end portion of a contact surface of the side fence portion, and a plurality of second relief groove portions penetrating in front-back direction at the lower end portion of the side fence portion. When pressing a material to be processed against the contact surface of the side fence portion, dust remaining between the side fence portion and the material to be processed can escape into the first and second relief groove portions. In turn, the dust can be prevented from intervening between the base and the material to be processed. Thus, it is not necessary for an operator to remove the dust on the base at each cutting process.