Included are a battery terminal connected to a battery post erected on a first surface of a battery, a battery connection unit provided with an electronic component connected to the battery terminal and to which ends of electric wires are connected, and a accommodating member that accommodates the battery terminal and the battery connection unit. The accommodating member has a through-hole through which the battery post is inserted, a terminal accommodating chamber in which a free end side of the battery post inserted through the through-hole is arranged and which accommodates the battery terminal connected to the free end side, and a butting portion that is projected from a periphery of the through-hole toward the first surface of the battery and made abut on the first surface.