The purpose of the invention is to enable high-speed computation of one or multiple actuator control target values related to engine control by means of a multicore processor. To achieve said purpose, multiple grid points arrayed in a two-dimensional Cartesian coordinate system having a first driving condition and a second driving condition as the axes thereof are associated in a one-to-one relationship with at least some of multiple cores that are placed in a grid in the multicore processor, said associations having the same sequence as the grid points in the two-dimensional Cartesian coordinate system; and a computation program for computing the optimum control value at each of the associated grid points is assigned to each of said cores. Each core that has an associated grid point is programmed to send the optimum control value at said associated grid point to an interpolation calculation core, said optimum control value having been computed by said core, and being sent to the interpolation calculation core if the driving area to which the current operation point belongs is an area defined by said associated grid point, said driving area being in the two-dimensional Cartesian coordinate system. The interpolation calculation core is programmed to perform an interpolation calculation of the optimum control value at the current operation point, by using the optimum control values at all the grid points that define the driving area to which the current operation point belongs, said driving area being in the two-dimensional Cartesian coordinate system. The multicore processor outputs the optimum control value at the current operation point as an actuator control target value, said optimum control value having been obtained from the interpolation calculation.