To provide an electronic controller for a vehicle which can keep the consistency between the contents of a stored database and the contents of a read-out database and download the contents of the databases in arbitrary timing (real time).

When the contents of a temporary buffer 53A are written to a database 55 at constant intervals of time, a CPU 51 starts and executes a database update routine DUR, and updates the database 55 according to the contents of the temporary buffer 53A when deciding that an in-access flag is not set by referring to a flag area in a work area 53B. When it is decided that the in-access flag is set in the flag area, the CPU 51 does not perform a writing process and reads data out of the database 55, thereby sending the data to an external request source.