A water temperature base increase correction amount for an internal combustion engine is reducingly corrected while maintaining the level of the surge-torque below a fixed level. A time constant for updating of the reduction correction is set based on a delay time from supply of fuel until generation of torque from combustion of the fuel. In this way responsiveness to the fuel reduction correction can be maintained, enabling improvement in fuel costs and exhaust emissions. Furthermore, the detection of the surge-torque necessary for example, for the control of fuel reduction correction, involves detection of scatter in combustion pressures between cylinders, while at the same time detecting variations in combustion pressure occurring in the same cylinder. The surge-torque level is then detected on the basis of these results. Since the influence or the occurrence of surge-torque is greater at low speed in the case of the former, and at high speed in the case of the latter, good surge-torque detection can be achieved over the whole operating range.