<p>A novel hybrid integrated circuit device (10) is disclosed, which is provided with: a box-shaped casing (56) which is made from a thermoplastic resin and in which a hole wall (57) is formed in a specified position; a chip-formed microcomputer (22) and its peripheral circuit elements (32), which are integrally formed with the casing and positioned in a sealed space formed by the casing; a non-volatile memory chip (30) positioned in a space enclosed by the hole wall; and an integrated circuit substrate (20) provided with external leads (50) routed on its peripheries. The specified electrodes of the microcomputer and the non-volatile memory chip are led out to each external leads through respective conductive paths (15) formed on the integrated circuit substrate (20) so that data can be written in the EPROM chip.</p>
