A stator comprising: a stator core including a yoke that extends annularly, and a plurality of stator teeth that is arranged on a peripheral surface of the yoke at intervals in a circumferential direction (D2) of the yoke , the stator core being annular and having slots , the slots being each provided between the stator teeth adjacent to each other in the circumferential direction (D2) of the stator core ; insulation members each disposed on the stator teeth in one end face of a pair of end faces of the stator core , the pair of end faces are aligned with each other in a thickness direction of the stator core ; a coil disposed in the slots , the coil protruding to the outside of the stator core through an opening of the slot located in the one end face; insulation paper disposed in each slot between the coil and the stator core , the insulation paper including side walls extending along the stator teeth , and the insulation paper including a bottom wall , the bottom wall extending along the circumferential direction (D2) of the yoke and being connected to the side walls , the insulation paper being provided so as to protrude through the openings of the slot located in the end faces , characterized by an internal surface of the stator core defining the slot has a recess at a position adjacent to connection parts between the side walls and the bottom wall of the insulation paper, the recess is formed in each slot and extends so as to be apart from the connection parts of the insulation paper in a radial direction and the circumferential direction, and the recess extends from the one end face in the thickness direction and each insulation member includes corresponding projections that are each configured to be disposed inside each recess . a stator core including a yoke that extends annularly, and a plurality of stator teeth that is arranged on a peripheral surface of the yoke at intervals in a circumferential direction (D2) of the yoke , the stator core being annular and having slots , the slots being each provided between the stator teeth adjacent to each other in the circumferential direction (D2) of the stator core ; insulation members each disposed on the stator teeth in one end face of a pair of end faces of the stator core , the pair of end faces are aligned with each other in a thickness direction of the stator core ; a coil disposed in the slots , the coil protruding to the outside of the stator core through an opening of the slot located in the one end face; insulation paper disposed in each slot between the coil and the stator core , the insulation paper including side walls extending along the stator teeth , and the insulation paper including a bottom wall , the bottom wall extending along the circumferential direction (D2) of the yoke and being connected to the side walls , the insulation paper being provided so as to protrude through the openings of the slot located in the end faces , characterized by an internal surface of the stator core defining the slot has a recess at a position adjacent to connection parts between the side walls and the bottom wall of the insulation paper, the recess is formed in each slot and extends so as to be apart from the connection parts of the insulation paper in a radial direction and the circumferential direction, and the recess extends from the one end face in the thickness direction and each insulation member includes corresponding projections that are each configured to be disposed inside each recess . <EOS>