A motor-driven compressor comprising: a compression mechanism configured to compress fluid; an electric motor configured to drive the compression mechanism; an inverter configured to control driving of the electric motor; a housing that accommodates the compression mechanism and the electric motor; and a cover fastened to the housing by fasteners (35a, 35b, 35c, 35d, 35e, 35f), the cover defining an accommodation chamber with the housing to accommodate the inverter, wherein the cover includes a plate-shaped body wall, and insertion holes (75a, 75b, 75c, 75d, 75e, 75f) extending through a periphery of the body wall, the fasteners (35a, 35b, 35c, 35d, 35e, 35f) being inserted through the insertion holes (75a, 75b, 75c, 75d, 75e, 75f), and the body wall includes a first surface opposed to the inverter in the accommodation chamber, a second surface located at a side opposite from the first surface, a first thickness portion having a first thickness (Tl), and a second thickness portion (713a, 713b, 713c, 713d) located around at least one of the insertion holes (75a, 75b, 75c, 75d, 75e, 75f), wherein the second thickness portion (713a, 713b, 713c, 713d) has a second thickness that is smaller than the first thickness and is obtained by recessing the body wall from the first surface toward the second surface, characterized in that the cover includes a circumferential wall extending from an outer edge of the body wall toward the housing, the insertion holes (75a, 75b, 75c, 75d, 75e, 75f) extend through the body wall and the circumferential wall, each of the second thickness portions (713a, 713b, 713c, 713d) extends around a corresponding one of the insertion holes (75a, 75b, 75c, 75d, 75e, 75f) to be concentric to the insertion hole (75a, 75b, 75c, 75d, 75e, 75f), and opposite ends of the second thickness portion (713a, 713b, 713c, 713d) in a circumferential direction connect to the circumferential wall. a compression mechanism configured to compress fluid; an electric motor configured to drive the compression mechanism; an inverter configured to control driving of the electric motor; a housing that accommodates the compression mechanism and the electric motor; and a cover fastened to the housing by fasteners (35a, 35b, 35c, 35d, 35e, 35f), the cover defining an accommodation chamber with the housing to accommodate the inverter, wherein the cover includes a plate-shaped body wall, and insertion holes (75a, 75b, 75c, 75d, 75e, 75f) extending through a periphery of the body wall, the fasteners (35a, 35b, 35c, 35d, 35e, 35f) being inserted through the insertion holes (75a, 75b, 75c, 75d, 75e, 75f), and a plate-shaped body wall, and insertion holes (75a, 75b, 75c, 75d, 75e, 75f) extending through a periphery of the body wall, the fasteners (35a, 35b, 35c, 35d, 35e, 35f) being inserted through the insertion holes (75a, 75b, 75c, 75d, 75e, 75f), and the body wall includes a first surface opposed to the inverter in the accommodation chamber, a second surface located at a side opposite from the first surface, a first thickness portion having a first thickness (Tl), and a second thickness portion (713a, 713b, 713c, 713d) located around at least one of the insertion holes (75a, 75b, 75c, 75d, 75e, 75f), wherein the second thickness portion (713a, 713b, 713c, 713d) has a second thickness that is smaller than the first thickness and is obtained by recessing the body wall from the first surface toward the second surface, a first surface opposed to the inverter in the accommodation chamber, a second surface located at a side opposite from the first surface, a first thickness portion having a first thickness (Tl), and a second thickness portion (713a, 713b, 713c, 713d) located around at least one of the insertion holes (75a, 75b, 75c, 75d, 75e, 75f), wherein the second thickness portion (713a, 713b, 713c, 713d) has a second thickness that is smaller than the first thickness and is obtained by recessing the body wall from the first surface toward the second surface, characterized in that the cover includes a circumferential wall extending from an outer edge of the body wall toward the housing, the insertion holes (75a, 75b, 75c, 75d, 75e, 75f) extend through the body wall and the circumferential wall, each of the second thickness portions (713a, 713b, 713c, 713d) extends around a corresponding one of the insertion holes (75a, 75b, 75c, 75d, 75e, 75f) to be concentric to the insertion hole (75a, 75b, 75c, 75d, 75e, 75f), and opposite ends of the second thickness portion (713a, 713b, 713c, 713d) in a circumferential direction connect to the circumferential wall.