To provide a booster and a booster circuit capable of reducing ESR of an aluminum electrolytic capacitor.

A fixing case 30, which is tubular to enclose an aluminum electrolytic capacitor 20, includes a first fixing terminal 31 and a second fixing terminal 32 that are electrically connected to a circuit wiring 63 and fixed to a circuit board 10, on one surface 11 side of the circuit board 10 of the tube. A current is caused to flow from the first fixing terminal 31 to the second fixing terminal 32 by way of the circuit wiring 63, to heat the fixing case 30, so that the aluminum electrolytic capacitor 20 is heated. Since the temperature of the aluminum electrolytic capacitor 20 rises, the ESR of the aluminum electrolytic capacitor 20 is reduced.