An outdoor unit (100, 100A, 100B) for an air-conditioning apparatus, the outdoor unit (100, 100A, 100B) comprising: a base plate having at least one hole for drainage; and a socket attached to the base plate with a clearance provided between the socket and a lower surface of the base plate, the socket communicating with the hole to form a first drainage path, wherein the clearance is provided so as to function as a second drainage path that allows drain water from the hole to be guided out of the outdoor unit (100, 100A, 100B) when the first drainage path is blocked, wherein the socket includes a base plate connection portion attached to the base plate, wherein the base plate connection portion includes an outer wall part that is hollow and serves as an outer wall of the base plate connection portion, the outer wall part being shaped so as to expand toward the base plate in side view, a lug having a first end connected to an inner surface of the outer wall part and a second end projecting beyond a top end of the outer wall part, and a catch having a first end connected to the inner surface of the outer wall part and a second end projecting beyond the second end of the lug, and wherein the catch extends through the hole and the second end of the lug is in contact with the lower surface of the base plate such that the clearance is provided between the top end of the outer wall part and the lower surface of the base plate. a base plate having at least one hole for drainage; and a socket attached to the base plate with a clearance provided between the socket and a lower surface of the base plate, the socket communicating with the hole to form a first drainage path, wherein the clearance is provided so as to function as a second drainage path that allows drain water from the hole to be guided out of the outdoor unit (100, 100A, 100B) when the first drainage path is blocked, wherein the socket includes a base plate connection portion attached to the base plate, wherein the base plate connection portion includes an outer wall part that is hollow and serves as an outer wall of the base plate connection portion, the outer wall part being shaped so as to expand toward the base plate in side view, a lug having a first end connected to an inner surface of the outer wall part and a second end projecting beyond a top end of the outer wall part, and a catch having a first end connected to the inner surface of the outer wall part and a second end projecting beyond the second end of the lug, and an outer wall part that is hollow and serves as an outer wall of the base plate connection portion, the outer wall part being shaped so as to expand toward the base plate in side view, a lug having a first end connected to an inner surface of the outer wall part and a second end projecting beyond a top end of the outer wall part, and a catch having a first end connected to the inner surface of the outer wall part and a second end projecting beyond the second end of the lug, and wherein the catch extends through the hole and the second end of the lug is in contact with the lower surface of the base plate such that the clearance is provided between the top end of the outer wall part and the lower surface of the base plate.