A stem has a stem body that has a first surface to be placed on a flexible substrate, a second surface opposite to the first surface, and a through hole passing through the first surface and the second surface, a cylindrical body that is fitted into the through hole of the stem body, and a lead that is inserted into the cylindrical body and fixed to the cylindrical body with a fixing member and that has an end portion protruding from the first surface of the stem body. The cylindrical body has a protrusion that protrudes toward the flexible substrate from the first surface of the stem body and surrounds an outer circumferential surface of the end portion of the lead.