To confirm in a short time that a timer circuit in an electronic control device is normal.

An onboard electronic control device includes a microcomputer which operates as power is supplied by the turning on of an ignition switch (IGSW), and a soak timer which is constantly supplied with power. The microcomputer performs a soak timer abnormality detection process each certain period of time when started as the IGSW is turned on. When the process is performed for the first time, the soak timer is started (S320), and a counter CT 1 for measuring the time (one count time) that a timer value, i.e., the count value of the soak timer, varies by one is cleared (S330). The counter CT 1 is incremented each time (S350), and if it is determined that the timer value has changed (S370: YES), a determination is made as to whether the soak timer is normal or abnormal according to the value of the counter value CT 1 at that time (S380-S395). Consequently, it is confirmed that the soak timer is normal in almost one count time.