A parameter setting circuit includes a first parameter setting unit configured to set a first parameter using first code signals generated by adjusting a value of parameter information to conform to a gear-down mode; a second parameter setting unit configured to generate pre-code signals by adjusting a value of the first code signals to conform to a specification of a second parameter, and set the second parameter using second code signals generated by adjusting a value of the pre-code signals according to a control signal; and a control section configured to generate the control signal according to whether it is the gear-down mode and whether the value of the first code signals is an odd number.