Provided is a target assembly configured so as to limit the occurrence of abnormal electric discharge between an extended portion of a backing plate and the side surface of a target while being able to reliably prevent the oozing of a bonding material for bonding the target to the backing plate to the outside. The backing plate (22) has an extended portion (22a) that extends outward past the outer circumferential edge of the target (21). A ring-shaped shield plate (4) is disposed facing the extended portion so as to surround the target when the target assembly (2) is attached to a sputtering device (SM). If the portion of the backing plate where the target is bonded is called a bonding portion (22b), said bonding portion protrudes with respect to the extended portion. The outer surface from the extended portion to the side surface of the bonding portion is roughened. An insulator film (23) is formed so as to span from the extended portion to the side surface of the target.