A booster comprising: a booster circuit comprising a power source terminal to which either one of start-up energy necessary for starting up the booster circuit and operation energy necessary for continuing an operation of the booster circuit is supplied, wherein the booster circuit generates a boosted output obtained by boosting an input voltage from a main power source as a target to be boosted; a selector circuit (218, 219) that outputs either one of the start-up energy and the operation energy to the booster circuit; and a power supply unit, different from the main power source, that supplies the start-up energy, wherein the booster circuit outputs all or a part of the boosted output to the selector circuit (218, 219) as the operation energy, the booster further comprising an output controller circuit that is provided in a stage subsequent to the booster circuit and performs output control to the boosted output obtained from the booster circuit, wherein the booster circuit comprises an oscillation control terminal for controlling an ability of boosting of the booster based on the output control by the output controller circuit, characterised in that boosting by the booster is enabled when a high logical signal is received at the oscillation control terminal, and the oscillation control terminal is connected to the power source terminal through an integrator circuit, or boosting by the booster is enabled when a low logical signal is received at the oscillation control terminal, and a PNP transistor or a P-type MOSFET level shifter circuit is arranged between the output controller circuit and the oscillation control terminal. a booster circuit comprising a power source terminal to which either one of start-up energy necessary for starting up the booster circuit and operation energy necessary for continuing an operation of the booster circuit is supplied, wherein the booster circuit generates a boosted output obtained by boosting an input voltage from a main power source as a target to be boosted; a selector circuit (218, 219) that outputs either one of the start-up energy and the operation energy to the booster circuit; and a power supply unit, different from the main power source, that supplies the start-up energy, wherein the booster circuit outputs all or a part of the boosted output to the selector circuit (218, 219) as the operation energy, the booster further comprising an output controller circuit that is provided in a stage subsequent to the booster circuit and performs output control to the boosted output obtained from the booster circuit, wherein the booster circuit comprises an oscillation control terminal for controlling an ability of boosting of the booster based on the output control by the output controller circuit, characterised in that boosting by the booster is enabled when a high logical signal is received at the oscillation control terminal, and the oscillation control terminal is connected to the power source terminal through an integrator circuit, or boosting by the booster is enabled when a low logical signal is received at the oscillation control terminal, and a PNP transistor or a P-type MOSFET level shifter circuit is arranged between the output controller circuit and the oscillation control terminal.