A cover set (510; 610; 810) that is configured to at least partially cover a tool accessory, which is mounted on a spindle that protrudes in a first direction from a housing (4, 6, 30) of a grinder (500; 600; 7800), the cover set comprising a first cover (520; 620; 820) that is provided in a circumferential direction of the spindle, is fixable to the housing (4, 6, 30), and at least partially covers the tool accessory, which is mounted on the spindle, from above with regard to the first direction when fixed to the housing (4, 6, 30), when the cover set is mounted to the grinder; and a second cover (570; 670; 870) for optional use that at least partially covers the tool accessory in association with the first cover (520; 620; 820) when the cover set is mounted to the grinder, wherein the second cover (570; 670; 870) is detachably mounted on the first cover (520; 620; 820), the second cover (570; 670; 870) is mountable on the first cover (520; 620; 820) in a plurality of orientations, an area of the tool accessory covered by the first cover (520; 620; 820) and the second cover (570; 670; 870) changes in accordance with the orientation of the second cover (570; 670; 870), when the cover set is mounted to the grinder, when the second cover (570; 670; 870) is mounted on the first cover (520; 620; 820) in a first orientation from among the plurality of orientations, an outer surface of an upper part of the first cover (520; 620; 820) with regard to the first direction and an inner surface of the second cover (570; 670; 870) that faces the tool accessory, when the cover set is mounted to the grinder, approach one another and the second cover (570; 670; 870) is housed on the outer-surface side of the upper part of the first cover (520; 620; 820) with regard to the first direction, when the second cover (570; 670; 870) is mounted on the first cover (520; 620; 820) in a second orientation from among the plurality of orientations, the inner surface of the second cover (570; 670; 870) opposes an inner surface of the first cover (520; 620; 820) that faces the tool accessory, when the cover set is mounted to the grinder, and a space that houses the tool accessory between the inner surface of the second cover (570; 670; 870) and the inner surface of the first cover (520; 620; 820) is formed, and thereby the second cover (570; 670; 870) at least partially covers, with regard to the first direction, an area below the tool accessory not covered by the first cover (520; 620; 820), the tool accessory is at least partially covered from below, when the cover set is mounted to the grinder, and when the second cover is mounted in the first orientation, when the cover set is mounted to the grinder, a user can perform a grinding process, and when the second cover is mounted in the second orientation, when the cover set is mounted to the grinder, the user can perform a cutting process. a first cover (520; 620; 820) that is provided in a circumferential direction of the spindle, is fixable to the housing (4, 6, 30), and at least partially covers the tool accessory, which is mounted on the spindle, from above with regard to the first direction when fixed to the housing (4, 6, 30), when the cover set is mounted to the grinder; and a second cover (570; 670; 870) for optional use that at least partially covers the tool accessory in association with the first cover (520; 620; 820) when the cover set is mounted to the grinder, wherein the second cover (570; 670; 870) is detachably mounted on the first cover (520; 620; 820), the second cover (570; 670; 870) is mountable on the first cover (520; 620; 820) in a plurality of orientations, an area of the tool accessory covered by the first cover (520; 620; 820) and the second cover (570; 670; 870) changes in accordance with the orientation of the second cover (570; 670; 870), when the cover set is mounted to the grinder, when the second cover (570; 670; 870) is mounted on the first cover (520; 620; 820) in a first orientation from among the plurality of orientations, an outer surface of an upper part of the first cover (520; 620; 820) with regard to the first direction and an inner surface of the second cover (570; 670; 870) that faces the tool accessory, when the cover set is mounted to the grinder, approach one another and the second cover (570; 670; 870) is housed on the outer-surface side of the upper part of the first cover (520; 620; 820) with regard to the first direction, when the second cover (570; 670; 870) is mounted on the first cover (520; 620; 820) in a second orientation from among the plurality of orientations, the inner surface of the second cover (570; 670; 870) opposes an inner surface of the first cover (520; 620; 820) that faces the tool accessory, when the cover set is mounted to the grinder, and a space that houses the tool accessory between the inner surface of the second cover (570; 670; 870) and the inner surface of the first cover (520; 620; 820) is formed, and thereby the second cover (570; 670; 870) at least partially covers, with regard to the first direction, an area below the tool accessory not covered by the first cover (520; 620; 820), the tool accessory is at least partially covered from below, when the cover set is mounted to the grinder, and when the second cover is mounted in the first orientation, when the cover set is mounted to the grinder, a user can perform a grinding process, and when the second cover is mounted in the second orientation, when the cover set is mounted to the grinder, the user can perform a cutting process.