A wiper arm (120, 220), swinging a wiper blade (110, 210) that wipes a surface to be wiped, comprising: an arm head in which a base end is attached to a swing shaft (15, 16); an arm shank in which a base end is attached to a tip of the arm head; an arm piece in which a base end is attached to a tip of the arm shank; a washer tube disposed along the arm head, the arm shank, and the arm piece; a washer nozzle attached to a tip of the washer tube; and a cover member covering at least the surrounding of a part of the arm piece and the washer tube in a longitudinal direction; wherein the cover member comprises: a first cover body, having a top wall portion, and a pair of side wall portions protruding from both sides of the top wall portion in a short-side direction; and a second cover body, attached to the pair of side wall portions and disposed to face the top wall portion, wherein the wiper arm (120, 220) is characterized by further comprising: an engagement convex portion, arranged at one of the washer nozzle and the cover member and protruding in the longitudinal direction of the arm piece; and an engagement concave portion, arranged at the other of the washer nozzle and the cover member and recessed in the longitudinal direction of the arm piece, with which the engagement convex portion is engaged, wherein the washer nozzle is fixed to the arm piece, and the cover member is arranged between the arm shank and the washer nozzle. an arm head in which a base end is attached to a swing shaft (15, 16); an arm shank in which a base end is attached to a tip of the arm head; an arm piece in which a base end is attached to a tip of the arm shank; a washer tube disposed along the arm head, the arm shank, and the arm piece; a washer nozzle attached to a tip of the washer tube; and a cover member covering at least the surrounding of a part of the arm piece and the washer tube in a longitudinal direction; wherein the cover member comprises: a first cover body, having a top wall portion, and a pair of side wall portions protruding from both sides of the top wall portion in a short-side direction; and a second cover body, attached to the pair of side wall portions and disposed to face the top wall portion, wherein the wiper arm (120, 220) is characterized by further comprising: an engagement convex portion, arranged at one of the washer nozzle and the cover member and protruding in the longitudinal direction of the arm piece; and an engagement concave portion, arranged at the other of the washer nozzle and the cover member and recessed in the longitudinal direction of the arm piece, with which the engagement convex portion is engaged, wherein the washer nozzle is fixed to the arm piece, and the cover member is arranged between the arm shank and the washer nozzle. a first cover body, having a top wall portion, and a pair of side wall portions protruding from both sides of the top wall portion in a short-side direction; and a second cover body, attached to the pair of side wall portions and disposed to face the top wall portion, wherein the wiper arm (120, 220) is characterized by further comprising: an engagement convex portion, arranged at one of the washer nozzle and the cover member and protruding in the longitudinal direction of the arm piece; and an engagement concave portion, arranged at the other of the washer nozzle and the cover member and recessed in the longitudinal direction of the arm piece, with which the engagement convex portion is engaged, wherein the washer nozzle is fixed to the arm piece, and the cover member is arranged between the arm shank and the washer nozzle. an engagement convex portion, arranged at one of the washer nozzle and the cover member and protruding in the longitudinal direction of the arm piece; and an engagement concave portion, arranged at the other of the washer nozzle and the cover member and recessed in the longitudinal direction of the arm piece, with which the engagement convex portion is engaged, wherein the washer nozzle is fixed to the arm piece, and the cover member is arranged between the arm shank and the washer nozzle.