A compressor comprising: a compression chamber forming member (30, 40) that forms a compression chamber (Sc); an injection passage that is formed in the compression chamber forming member (30, 40) and/or a separate member disposed in a surrounding area thereof and connects to the compression chamber (Sc); an injection pipe configured to supply refrigerant to the injection passage; and a pulsation attenuation space (31c, 330, 340) that is formed, so as to communicate with the injection passage, in the compression chamber forming member (30, 40) or the separate member disposed in the surrounding area and is configured to attenuate pulsation of refrigerant gas flowing from the injection pipe into the compression chamber (Sc), wherein: the compression chamber (Sc) and the injection passage communicate with each other by an injection port; the pulsation attenuation space is an expansion chamber having a larger flow path cross-sectional area than the flow path cross-sectional area of the injection port; and the compressor has a configuration where the injection port lies on an extension line of the direction in which the refrigerant is to flow out of the expansion chamber, characterized in that: the compressor has a configuration where the direction in which the refrigerant is to flow into the expansion chamber and the direction in which the refrigerant is to flow out of the expansion chamber intersect each other; and a flow path cross section on the refrigerant outflow side of the expansion chamber and a flow path cross section of the injection port have a positional relationship where they are parallel to each other and the area centers of the flow path cross sections do not lie on the same axis. a compression chamber forming member (30, 40) that forms a compression chamber (Sc); an injection passage that is formed in the compression chamber forming member (30, 40) and/or a separate member disposed in a surrounding area thereof and connects to the compression chamber (Sc); an injection pipe configured to supply refrigerant to the injection passage; and a pulsation attenuation space (31c, 330, 340) that is formed, so as to communicate with the injection passage, in the compression chamber forming member (30, 40) or the separate member disposed in the surrounding area and is configured to attenuate pulsation of refrigerant gas flowing from the injection pipe into the compression chamber (Sc), wherein: the compression chamber (Sc) and the injection passage communicate with each other by an injection port; the pulsation attenuation space is an expansion chamber having a larger flow path cross-sectional area than the flow path cross-sectional area of the injection port; and the compressor has a configuration where the injection port lies on an extension line of the direction in which the refrigerant is to flow out of the expansion chamber, the compression chamber (Sc) and the injection passage communicate with each other by an injection port; the pulsation attenuation space is an expansion chamber having a larger flow path cross-sectional area than the flow path cross-sectional area of the injection port; and the compressor has a configuration where the injection port lies on an extension line of the direction in which the refrigerant is to flow out of the expansion chamber, characterized in that: the compressor has a configuration where the direction in which the refrigerant is to flow into the expansion chamber and the direction in which the refrigerant is to flow out of the expansion chamber intersect each other; and a flow path cross section on the refrigerant outflow side of the expansion chamber and a flow path cross section of the injection port have a positional relationship where they are parallel to each other and the area centers of the flow path cross sections do not lie on the same axis. the compressor has a configuration where the direction in which the refrigerant is to flow into the expansion chamber and the direction in which the refrigerant is to flow out of the expansion chamber intersect each other; and a flow path cross section on the refrigerant outflow side of the expansion chamber and a flow path cross section of the injection port have a positional relationship where they are parallel to each other and the area centers of the flow path cross sections do not lie on the same axis.