A compound semiconductor device, comprising: a substrate; a compound semiconductor stacked structure of nitride over the substrate; a passivation film that covers the compound semiconductor stacked structure; a gate electrode, a source electrode, and a drain electrode at a level above the compound semiconductor stacked structure; a field plate that is connected to the source electrode and extends to between the gate electrode and the drain electrode; and an Si-C bond containing film (416, 916) that contains an Si-C bond and includes a first part, a second part and a third part between the source electrode and the drain electrode, the passivation film being formed above the Si-C bond containing film (416, 916), the first part being between an end portion of the drain electrode side of the gate electrode and the compound semiconductor stacked structure in a thickness direction and contacting at least a part of an upper surface of the compound semiconductor stacked structure, the second part being between an end portion of the drain electrode side of the field plate and the compound semiconductor stacked structure in a thickness direction and contacting at least a part of an upper surface of the compound semiconductor stacked structure, and the third part being between an end portion of the source electrode side of the gate electrode and the compound semiconductor stacked structure in a thickness direction and contacting at least a part of an upper surface of the compound semiconductor stacked structure; an opening formed in the passivation film and the Si-C bond containing film (416, 916) between the source electrode and the drain electrode, wherein the gate electrode contacts the compound semiconductor stacked structure through the opening so as to form a Schottky junction with the compound semiconductor stacked structure; an end portion of the source electrode side of the Si-C bond containing film (416, 916) being apart from an end portion of the gate electrode side of the source electrode, an end portion of the drain electrode side of the Si-C bond containing film (416, 916) being apart from an end portion of the gate electrode side of the drain electrode. a substrate; a compound semiconductor stacked structure of nitride over the substrate; a passivation film that covers the compound semiconductor stacked structure; a gate electrode, a source electrode, and a drain electrode at a level above the compound semiconductor stacked structure; a field plate that is connected to the source electrode and extends to between the gate electrode and the drain electrode; and an Si-C bond containing film (416, 916) that contains an Si-C bond and includes a first part, a second part and a third part between the source electrode and the drain electrode, the passivation film being formed above the Si-C bond containing film (416, 916), the first part being between an end portion of the drain electrode side of the gate electrode and the compound semiconductor stacked structure in a thickness direction and contacting at least a part of an upper surface of the compound semiconductor stacked structure, the second part being between an end portion of the drain electrode side of the field plate and the compound semiconductor stacked structure in a thickness direction and contacting at least a part of an upper surface of the compound semiconductor stacked structure, and the third part being between an end portion of the source electrode side of the gate electrode and the compound semiconductor stacked structure in a thickness direction and contacting at least a part of an upper surface of the compound semiconductor stacked structure; an opening formed in the passivation film and the Si-C bond containing film (416, 916) between the source electrode and the drain electrode, wherein the gate electrode contacts the compound semiconductor stacked structure through the opening so as to form a Schottky junction with the compound semiconductor stacked structure; an end portion of the source electrode side of the Si-C bond containing film (416, 916) being apart from an end portion of the gate electrode side of the source electrode, an end portion of the drain electrode side of the Si-C bond containing film (416, 916) being apart from an end portion of the gate electrode side of the drain electrode.