A semiconductor integrated circuit device has, as a current monitor circuit, a circuit in which n-channel type MISFETs are connected in series with each other. Based on a delay time of a speed monitor circuit in a state where a substrate bias is being applied to the p-channel type MISFETs, a first voltage value of a first substrate bias to be applied to the p-channel type MISFETs is determined. Next, based on a current flowing through an n-channel type MISFET in a state where the first substrate bias is being applied to the p-channel type MISFETs of the current monitor circuit and a second substrate bias is being applied to the n-channel type MISFETs of the current monitor circuit, a second voltage value of the second substrate bias to be applied to the n-channel type MISFETs is determined.