Provided is an in-vehicle control device that allows the giving and receiving of data via inter-core communication at the timing of a user, as well as being capable of minimizing processing load while satisfying safety requirements of different functional safety levels in the inter-core communication of a multicore microcomputer. The data communication between a plurality of cores is performed by a writing means for writing the data of a core register into a region of a shared memory of the cores, where safety levels are set, using a hardware function. The cores have different functional safety levels.