A notch antenna includes a ground conductor having a slit and a reactance circuit containing a capacitive reactance element and an inductive reactance element, the reactance circuit being placed at an open end of the slit so as to bridge the slit and being connected to the ground conductor. The slit has a closed end to which power is supplied, and the capacitance of the capacitive reactance element and the inductance of the inductive reactance element are set so that the reactance circuit has a capacitance desired to obtain a first antenna resonance point at a first frequency and a capacitance desired to obtain a second antenna resonance point at a second frequency.