To reduce variations in characteristics due to diode elements or assembling and to reduce an adjustment time for permitting an attenuating amount and its frequency characteristic to be a desired value by providing a multi-diode chip where the plurality of diode elements are formed in parallel on the same semi-conductor chip.

An attenuating circuit is constituted of the multi-diode chip 2 where n(n is a ≥2 integer) diode elements 1 are arranged in parallel on the same semi-conductor chip, n input matching circuits 3 corresponding to the n diode elements 1 and n output matching circuits 4. The n diode elements 1 which are continuously formed on a semi-conductor wafer are segmented as one chip being the multi-diode chip 2. The n diode elements 1 are mounted in a one-chip state which is formed on the multi-diode chip 2.