An electronic control unit (ECU) having multiple layers of distributed network control functionality is used to facilitate development of complicated vehicle control network system. That is, for example, three layers of distributed network control functionality are devised in the ECU. The three layers of functionality include a so-called application layer that provides a structurally functional framework of function reusability, extensibility and independence as well as an interface (I/F) for functional context, a so-called system infrastructure layer that uniformly manages system resources for an entire system development scheme based on a rule, and a so-called hardware abstraction layer that controls hardware system as an abstractive object including electrical property of devices such as ECUs, sensors and/or actuators as well as a network itself.