A memory of a parameter setting apparatus stores therein a current value of a signal processing parameter and an auxiliary value for temporarily adjusting the current value. Once an instruction for changing the current value of the parameter is given by an operation, by a user, of a manual operator when an edit mode is ON, a CPU of the parameter setting apparatus not only changes the current value but also changes the auxiliary value in response to the current value change instruction. When the edit mode is OFF, on the other hand, the CPU changes only the current value in response to the current value change instruction without changing the auxiliary value.