the present invention is made to resolve problems of the above described prior art . prime object of the present invention is to provide an oscillator circuit capable of outputting oscillation signal with stable oscillation frequency , a semiconductor device and a semiconductor memory device provided with the oscillator circuit , and control method of the oscillator circuit . for achieving the prime object , there are taken the following countermeasures at the time of initiating oscillation where the inventive oscillator circuit can control to operate / stop oscillation . that is , the countermeasures to be taken are : oscillation operation is stopped or an output of an oscillation signal is not permitted while transient oscillation frequency is unstable ; or a period that transient oscillation frequency is unstable is shortened .