A grinder includes a motor, a housing, a spindle and a cover. The spindle protrudes downward from the housing, is driven by the motor, and thereby rotates. The cover at least partially covers a tool accessory mounted on the spindle. The cover includes a first cover part and a second cover part. The first cover part is fixed to the housing and at least partially covers the tool accessory from above. The second cover part is held such that it is capable of moving relative to the first cover part. The grinder is configured such that the area of the tool accessory covered by the cover changes in accordance with the relative movement.