A cryocooler includes an expander that includes a cooling stage, an exhaust temperature sensor that measures an exhaust temperature which is a temperature of a working gas exhausted from the expander and outputs an exhaust temperature signal indicating the measured exhaust temperature, and a controller that compares, during execution of initial cooling in which the cooling stage is cooled from an initial temperature to a cryogenic temperature, the measured exhaust temperature to a reference temperature based on the exhaust temperature signal and completes the initial cooling in a case where a temperature difference between the measured exhaust temperature and the reference temperature is within a reference range.