A rectifier including an autonomous type synchronous-rectification MOSFET is provided, which prevents chattering and through-current caused by a malfunction when a noise is applied. The rectifier includes: a rectification MOSFET for performing synchronous rectification; a determination circuit configured to input a voltage between a pair of main terminals of the rectification MOSFET, and to determine whether the rectification MOSFET is in on or off state on the basis of the inputted voltage; and a gate drive circuit configured such that a gate of the rectification MOSFET is turned on and off by a comparison signal from the determination circuit, and such that a time required to boost a gate voltage when the rectification MOSFET is turned on is longer than a time required to lower the gate voltage when the rectification MOSFET is turned off.