A rotating machine, comprising: a core provided with slots extending in the axial direction of the core, which are in communication with the core along said axial direction; a winding provided in the slots; and an insulating member provided between each slot and the winding; wherein in the insulating member, a first inclined surface is provided on an insertion side of the insulating member into the slot along said axial direction and a second inclined surface is provided on an insertion side of the winding into the insulating member along said axial direction, wherein the insulating member is a sheet-shaped insulator which is bent into a cylindrical shape, and is provided with said first and second inclined surfaces, and an angle formed between an inner peripheral surface of the insulating member and the first inclined surface for making it easy to insert the insulating member into the slot is different from an angle formed between the inner peripheral surface of the insulating member and the second inclined surface for making it easy to insert the winding into the insulating member, wherein the first inclined surface constitutes a convex end of the insulating member; and the first inclined surface inclines toward the slot such that the convex end is narrowed in the insertion direction into the core, and the second inclined surface constitutes a concave end of the insulating member, formed on the opposite side of the convex end; and the second inclined surface inclines toward the winding such that an opening formed by the cylindrical shape of the insulating member becomes greater toward a direction opposite from the insertion direction of winding. a core provided with slots extending in the axial direction of the core, which are in communication with the core along said axial direction; a winding provided in the slots; and an insulating member provided between each slot and the winding; wherein in the insulating member, a first inclined surface is provided on an insertion side of the insulating member into the slot along said axial direction and a second inclined surface is provided on an insertion side of the winding into the insulating member along said axial direction, wherein the insulating member is a sheet-shaped insulator which is bent into a cylindrical shape, and is provided with said first and second inclined surfaces, and an angle formed between an inner peripheral surface of the insulating member and the first inclined surface for making it easy to insert the insulating member into the slot is different from an angle formed between the inner peripheral surface of the insulating member and the second inclined surface for making it easy to insert the winding into the insulating member, wherein the first inclined surface constitutes a convex end of the insulating member; and the first inclined surface inclines toward the slot such that the convex end is narrowed in the insertion direction into the core, and the second inclined surface constitutes a concave end of the insulating member, formed on the opposite side of the convex end; and the second inclined surface inclines toward the winding such that an opening formed by the cylindrical shape of the insulating member becomes greater toward a direction opposite from the insertion direction of winding.