A rotary compressor comprising: a compression mechanism ; a casing having a cylindrical portion and covering the compression mechanism; a motor stator including a core being constituted by stacking a plurality of steel plates , the stacked steel plates being fixed to an inner surface of the cylindrical portion, the core including an annular portion and teeth and slots , the number of the teeth and the number of the slots are nine; and a motor rotor configured to rotate a crankshaft that is configured to drive the compression mechanism, wherein the stacked steel plates have areas provided radially outside the nine teeth disposed at equal intervals along a circumference of the annular portion and assumed as a first area (A441) to a ninth area (A449); characterized in that the stacked steel plates have first concave portions provided respectively in five of the first to ninth areas, the stacked steel plates further have a second concave portion in at least one of four areas other than the five areas including the first concave portions, the five first concave portions and an inner circumferential surface of the cylindrical portion constitute five first passages allowing communication between a first side and a second side of the motor stator, the second concave portion and the inner circumferential surface of the cylindrical portion constitute at least one second passage allowing communication between the first side and the second side of the motor stator, the first passages each have a sectional area larger than a sectional area of the second passage, in the four areas other than the five areas where the first passage is located, no passage has a sectional area equal to or larger than the sectional area of the first passage , and the five first passages are provided respectively in the first area (A441), the third area (A443), the fourth area (A444), the sixth area (A446), and the eighth area (A448). a compression mechanism ; a casing having a cylindrical portion and covering the compression mechanism; a motor stator including a core being constituted by stacking a plurality of steel plates , the stacked steel plates being fixed to an inner surface of the cylindrical portion, the core including an annular portion and teeth and slots , the number of the teeth and the number of the slots are nine; and a motor rotor configured to rotate a crankshaft that is configured to drive the compression mechanism, wherein the stacked steel plates have areas provided radially outside the nine teeth disposed at equal intervals along a circumference of the annular portion and assumed as a first area (A441) to a ninth area (A449); the stacked steel plates have first concave portions provided respectively in five of the first to ninth areas, the stacked steel plates further have a second concave portion in at least one of four areas other than the five areas including the first concave portions, the five first concave portions and an inner circumferential surface of the cylindrical portion constitute five first passages allowing communication between a first side and a second side of the motor stator, the second concave portion and the inner circumferential surface of the cylindrical portion constitute at least one second passage allowing communication between the first side and the second side of the motor stator, the first passages each have a sectional area larger than a sectional area of the second passage, in the four areas other than the five areas where the first passage is located, no passage has a sectional area equal to or larger than the sectional area of the first passage , and the five first passages are provided respectively in the first area (A441), the third area (A443), the fourth area (A444), the sixth area (A446), and the eighth area (A448). <EOS>