One embodiment provides a phase-locked loop (PLL), in which a sequencer controls a loop filter such that, when a signal indicating turning-off of a power supply of the PLL is input thereto, or when a signal indicating turning-on of the power supply of the PLL is input thereto, a resistance value of a first resistance change device in the loop filter is a first resistance value, and that, after the PLL is stabilized, the resistance value of the first resistance change device is a second resistance value which is higher than the first resistance value.