Abstract: The power source unit utilizes a pair of connecting terminal pieces, each having a planar base portion bonded to one of positive and negative terminals of a power source element, and a planar top end portion twisted perpendicular to the planar base portion and designed to connected to a circuit board for mounting of the power source element. By such construction, the total mounting height of the power source element and the circuit board can be reduced, and the connecting strength can be improved between the power source element and the circuit board.