A magnetoresistive effect device includes a magnetoresistive effect element first and second ports, a signal line, an inductor, and a direct current input terminal. The first port, the magnetoresistive effect element, and the second port are connected in series in this order via the signal line. The inductor is connected to one of the signal line between the magnetoresistive effect element and the first port and the signal line between the magnetoresistive effect element and the second port and is capable of being connected to ground. The direct-current input terminal is connected to the other of the above signal lines. A closed circuit including the magnetoresistive effect element, the signal line, the inductor, the ground, and direct-current input terminal is capable of being formed. The magnetoresistive effect element is arranged so that direct current flows in a direction from a magnetization fixed layer to a magnetization free layer.