An electronic circuit includes a constant voltage output circuit that outputs a constant voltage and a step-up circuit including an input portion to which outputs of the constant voltage output circuit are connected and is controlled by a control circuit, an overcurrent detecting circuit that detects overcurrent when current of not less than a specified value is supplied to the constant voltage output circuit by not less than a first specified period of time, and an overcurrent protecting circuit that performs operations of protecting the constant current output circuit based on outputs of the overcurrent detecting circuit. The electronic circuit protects, in an electronic circuit using a charge pump type step-up circuit, the step-up circuit from overcurrent in abnormal conditions and achieves more rapid operations.