A workpiece holding jig includes a back panel and a frame body, the frame body includes a main body having an annular shape, a conductive member provided all over the main body, a contact member provided along the conductive member, the contact member being electrically connected to the conductive member to come into electrical contact with a peripheral portion of the workpiece, and a seal member provided all over the main body and located on an inner side of the main body relative to the contact member, the frame body is adapted to form a sealed space that accommodates the peripheral portion of the workpiece, the conductive member, and the contact member in a state where the seal member and the contact member are in contact with the peripheral portion, and the frame body includes a liquid inlet through which a liquid is injected into the sealed space.