To provide a surface-mounting type electronic circuit unit suitable for miniaturization, circuit elements including capacitors (C), resistors (R) and inductance elements (L) and a conductive pattern (P) connected to these circuit elements are thinly formed on an alumina substrate (1), semiconductor bare chips for a diode and a transistor are bonded on a connection land of the conductive pattern via wire, an inductance element composed of a pair of conductors opposite at a predetermined interval on the aluminum board is thinly formed and a unbalance/balance converter is formed by these conductors.