A step-up circuit comprises a rectifier element 11 provided on a current path from a terminal VCC applied with a voltage source voltage VCC to a terminal VP connected to one electrode of a capacitor C1 such that a direction from the terminal VCC toward the terminal VP is a forward direction, a rectifier element 12 provided on a portion of the current path which is between the rectifier element 11 and the terminal VP such that a direction from the rectifier element 11 toward the terminal VP is a forward direction, a terminal BC1 which is connected to one electrode of a capacitor C2 and is applied with an oscillating voltage, a terminal BC2 which is connected to a portion of the current path which is between the rectifier element 11 and the rectifier element 12 and is connected to the other electrode of the capacitor C2, and a switching element 14 provided on a portion of the current path which is between a connection point, where the terminal BC2 is connected to the current path, and the terminal VCC, and the switching element 14 is configured to be turned ON and OFF according to the voltage at the terminal VP with respect to the voltage at the terminal BC2.