To provide a signal generator, with which frequency hopping can be performed at high speed and further frequency stability is high.

The signal generator for frequency hopping is provided with a first PLL circuit and a second PLL circuit for synchronizing phases to the same reference frequency, the first and second PLL circuits are alternately phase-locked from a frequency pull-in process and the oscillation frequencies of the first and second PLL circuit in the phase-locked state are alternately outputted.