there is provided a compound semiconductor device having a capacitor , to prevent a leakage current flowing between an upper electrode and a lower electrode of the capacitor via an insulating protective film . the compound semiconductor device comprises a first electrode of a capacitor formed on a compound semiconductor substrate via a first insulating film , a dielectric film of the capacitor formed on the first electrode , a second electrode of a capacitor formed on the dielectric film , a second insulating film for covering an upper surface and side surfaces of the second electrode , and an insulating protective film for covering the second insulating film , the dielectric film , the first electrode and the first insulating film , and having a hydrogen containing rate which is larger than the second insulating film .