A rotary electric machine configured to be cooled by flowing a coolant on an outer periphery, the rotary electric machine comprising: a stator; a housing being a cylindrical member housing the stator on an inner periphery of the housing, the housing including a flow passage groove formed so as to be recessed in a circumferential direction on the outer periphery of the housing, the housing including on the outer periphery an annular first protruding portion and an annular second protruding portion facing each other in an axial direction via the flow passage groove and protruding in a radial direction; a cover covering the outer periphery of the housing and contacting with the first protruding portion and the second protruding portion; characterized in further comprising: a partition plate having one end disposed in a first cutout provided to the first protruding portion and the other end disposed in a second cutout provided to the second protruding portion, the partition plate arranged in axial direction and partitioning the flow passage groove in the circumferential direction, wherein: the first cutout is larger in width than the second cutout in the circumferential direction; and the one end of the partition plate is formed to be equal in width to the first cutout, and the other end of the partition plate is formed to be equal in width to the second cutout. a stator; a housing being a cylindrical member housing the stator on an inner periphery of the housing, the housing including a flow passage groove formed so as to be recessed in a circumferential direction on the outer periphery of the housing, the housing including on the outer periphery an annular first protruding portion and an annular second protruding portion facing each other in an axial direction via the flow passage groove and protruding in a radial direction; a cover covering the outer periphery of the housing and contacting with the first protruding portion and the second protruding portion; characterized in further comprising: a partition plate having one end disposed in a first cutout provided to the first protruding portion and the other end disposed in a second cutout provided to the second protruding portion, the partition plate arranged in axial direction and partitioning the flow passage groove in the circumferential direction, wherein: the first cutout is larger in width than the second cutout in the circumferential direction; and the one end of the partition plate is formed to be equal in width to the first cutout, and the other end of the partition plate is formed to be equal in width to the second cutout. a partition plate having one end disposed in a first cutout provided to the first protruding portion and the other end disposed in a second cutout provided to the second protruding portion, the partition plate arranged in axial direction and partitioning the flow passage groove in the circumferential direction, wherein: the first cutout is larger in width than the second cutout in the circumferential direction; and the one end of the partition plate is formed to be equal in width to the first cutout, and the other end of the partition plate is formed to be equal in width to the second cutout. the first cutout is larger in width than the second cutout in the circumferential direction; and the one end of the partition plate is formed to be equal in width to the first cutout, and the other end of the partition plate is formed to be equal in width to the second cutout.