To provide a highly-reliable and high-voltage compound semiconductor device which ensures sufficient breakdown voltage though a current collapse phenomenon is reduced by using an Al-containing protection film.

The compound semiconductor device comprises: a compound semiconductor laminated structure 2; a source electrode 5 and a drain electrode 6 which are formed above the compound semiconductor laminated structure 2 and at a distance from each other; a gate electrode 4 formed above the compound semiconductor laminated structure 2 and between the source electrode 5 and the drain electrode 6; and a passivation film 3a which is formed above the compound semiconductor laminated structure 2 and composed of an Al-containing insulation material. The passivation film 3a is in a non-contact state with the compound semiconductor laminated structure 2 under the source electrode 5 and under the drain electrode 6.