A circular saw includes a table having an upper surface for placing a workpiece thereon. A saw unit has a saw blade mounted thereon and is supported on the table such that the saw unit is movable in a horizontal direction parallel to the upper surface of the table and is movable in a vertical direction perpendicular to the upper surface of the table. At least one of a first lock device and a second lock device is provided. The first lock device is operable to prevent the saw unit from moving in the horizontal direction in response to the movement of the saw unit in the vertical direction. The second lock device is operable to prevent the saw unit from moving in the vertical direction in response to the movement of the saw unit in the horizontal direction.