Disclosed is a hybrid integrated circuit device provided with an active filter. The active filter is constructed mainly from a rectifier circuit, a reactor with one terminal connected with an output terminal of the rectifier, a switching element connected with one terminal of the reactor and a smoothing condenser connected with the other terminal of the reactor. The active filter is mounted on an insulating metal substrate and has, other than the above feature, a specific circuit structure wherein the substrate is divided by a ground pattern or power supply pattern into two blocks. One block is for a large current circuit such as the rectifier circuit, the switching element, and a diode and another block for a small signal circuit such as a control circuit. The hybrid integrated circuit device is of remarkably compact size. Also, it is greatly superior in a noise performance because switching noise does not flow into the chassis of electronic equipment from the metal substrate and the control circuit is shielded from the noise produced by the large current circuit, and also because the noise caused by wiring inductance can be limited.