A pulse generator for UWB transmission, lower power consumption, and suppression of LO leakage by nonuse of the LO signal. The pulse generator includes a clock generator (CLK) for giving clock of a predetermined period; a delay circuit (DLY) equipped with a function of controlling a delay time and for delaying the clock; a square-wave pulse generation circuit (SWPG) that receives information being spread by a spread code and modulates phases of square wave pulses that have a pulse width corresponding to a differential delay for one stage of the delay circuit; and an amplitude control unit (AMPC) that outputs an impulse sequence having the pulse width of the square wave in a predetermined amplitude and combines the impulses; and outputs pulses that have a predetermined envelope form.