PURPOSE: To provide a multicomputer system for automobile which is easy to use and is capable of simplifying the flow of processing.

CONSTITUTION: This multicomputer system consists of at least two computers 12, 14 and executes a first processing step array (cold start routine) when a power source is on. The system executes a second processing step array (warm start routine) at the time of a new start during operation. The system is provided with means which discriminate the power source on and the new start and select the processing step array corresponding thereto. Further, whether the reset times of the computer exceed a prescribed threshold value or not is checked. In the case of affirmative, the computer is shifted to the standby state during this operation cycle.