A secondary battery device 1 including multiple protective circuits U.sub.1-U.sub.3 connected in parallel and each having two fuses f.sub.a, f.sub.b connected in series, wherein a terminal t.sub.c of each heater h is connected to a switch element 4 via rectifier element D.sub.1-D.sub.3. Even if a potential difference is generated between terminals t.sub.c, no residual current flows because any one of the rectifier elements D.sub.1-D.sub.3 is reverse-biased.