A rotary compressor comprising a housing that houses a motor including a motor stator and a refrigerant gas compressor driven by the motor, the motor stator including - a substantially cylindrical stator iron core including -- a ring-like yoke, -- teeth that radially extend from the yoke toward a center, and -- a plurality of U-shaped grooves that are formed on a circumference of the yoke in an axial direction; and - insulators as insulating coatings on axial-direction ends of the stator iron core, the insulators each including -- a ring-like outer circumference wall, -- a plurality of tooth covering portions provided at end faces of the teeth and radially extending from the outer circumference wall toward a center, -- at least three engagement claws (35a, 35b, 35c) that are located spaced apart in a circumferential direction on outside of the outer circumference wall and fitted in axial-direction ends of the U-shaped grooves, respectively, characterized by - protrusions that extend from inner ends of the tooth covering portions in the axial direction, respectively, and in that - one of the engagement claws (35a, 35b, 35c) is arranged such that a first circumferential-direction side portion of the engagement claw is in contact with a first side wall of one of the U-shaped grooves, - another one of the engagement claws (35a, 35b, and 35c) is arranged such that a second circumferential-direction side portion of the engagement claw is in contact with a second side wall of another one of the U-shaped grooves, and - the U-shaped grooves of the stator iron core serve as return passages of refrigerant oil lubricating the refrigerant gas compressor. - a substantially cylindrical stator iron core including -- a ring-like yoke, -- teeth that radially extend from the yoke toward a center, and -- a plurality of U-shaped grooves that are formed on a circumference of the yoke in an axial direction; and -- a ring-like yoke, -- teeth that radially extend from the yoke toward a center, and -- a plurality of U-shaped grooves that are formed on a circumference of the yoke in an axial direction; and - insulators as insulating coatings on axial-direction ends of the stator iron core, the insulators each including -- a ring-like outer circumference wall, -- a plurality of tooth covering portions provided at end faces of the teeth and radially extending from the outer circumference wall toward a center, -- at least three engagement claws (35a, 35b, 35c) that are located spaced apart in a circumferential direction on outside of the outer circumference wall and fitted in axial-direction ends of the U-shaped grooves, respectively, characterized by -- a ring-like outer circumference wall, -- a plurality of tooth covering portions provided at end faces of the teeth and radially extending from the outer circumference wall toward a center, -- at least three engagement claws (35a, 35b, 35c) that are located spaced apart in a circumferential direction on outside of the outer circumference wall and fitted in axial-direction ends of the U-shaped grooves, respectively, - protrusions that extend from inner ends of the tooth covering portions in the axial direction, respectively, and in that - one of the engagement claws (35a, 35b, 35c) is arranged such that a first circumferential-direction side portion of the engagement claw is in contact with a first side wall of one of the U-shaped grooves, - another one of the engagement claws (35a, 35b, and 35c) is arranged such that a second circumferential-direction side portion of the engagement claw is in contact with a second side wall of another one of the U-shaped grooves, and - the U-shaped grooves of the stator iron core serve as return passages of refrigerant oil lubricating the refrigerant gas compressor.