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 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 as the operation energy, the booster further comprising an output controller circuit (239-243) 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 (239-243), 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 (239-243) 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 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 as the operation energy, the booster further comprising an output controller circuit (239-243) 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 (239-243), 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 (239-243) and the oscillation control terminal . <EOS>