To provide an inexpensive and easy-to-manufacture battery unit to be mainly used in various types of electronic equipment, reliably protecting an electronic circuit.

A switching element 14 is covered with an insulating resin 15, and a temperature fuse 16 is placed in a grooved portion 15A of the insulating resin 15. Since the temperature fuse 16 is placed right over the switching element 14, heat generated in the switching element 14 can be reliably conducted to the temperature fuse 16, the electronic circuit can be reliably protected, and an area which these occupies on a wiring board 11 be reduced. Besides, since the temperature fuse 16 is placed and soldered into the grooved portion 15A, the inexpensive and easy-to-manufacture battery unit is provided.