A compressor (100, 200) comprising: a piston (260-1, 260-2, 260-3) having formed therein a suction space, in which refrigerant gas is sucked; and a cylinder (140, 240, 240-1, 240-2) in which the piston (260-1, 260-2, 260-3) is accommodated, the cylinder (140, 240, 240-1, 240-2) defining a compression space that is configured, based on the piston (260-1, 260-2, 260-3) reciprocating in an axial direction, to compress the refrigerant gas therein, wherein a gas inflow passage of which one side communicates with a gas pocket outside the cylinder (140, 240, 240-1, 240-2) and the other side communicates with a space formed in the cylinder (140, 240, 240-1, 240-2) is formed in the cylinder (140, 240, 240-1, 240-2), and wherein0 the piston (260-1, 260-2, 260-3) comprises: a guide having a cylindrical shape; a head positioned at a front side of the guide; and a plurality of fine irregularities (265, 266, 267) including fine grooves or fine pores formed in an outer circumferential surface of the guide facing the cylinder (140, 240, 240-1, 240-2) and provided at a position corresponding to the gas inflow passage, characterized in that the plurality of fine irregularities (265, 266, 267) include: a plurality of second fine irregularities recessed from the outer circumferential surface of the guide, extending in a circumferential direction of the guide to have a circular band shape and arranged in an axial direction; and a plurality of first fine irregularities recessed from an inner surface of each of the second fine irregularities and formed to be spaced apart from each other in a circumferential direction of the second fine irregularities. a piston (260-1, 260-2, 260-3) having formed therein a suction space, in which refrigerant gas is sucked; and a cylinder (140, 240, 240-1, 240-2) in which the piston (260-1, 260-2, 260-3) is accommodated, the cylinder (140, 240, 240-1, 240-2) defining a compression space that is configured, based on the piston (260-1, 260-2, 260-3) reciprocating in an axial direction, to compress the refrigerant gas therein, wherein a gas inflow passage of which one side communicates with a gas pocket outside the cylinder (140, 240, 240-1, 240-2) and the other side communicates with a space formed in the cylinder (140, 240, 240-1, 240-2) is formed in the cylinder (140, 240, 240-1, 240-2), and wherein0 the piston (260-1, 260-2, 260-3) comprises: a guide having a cylindrical shape; a head positioned at a front side of the guide; and a plurality of fine irregularities (265, 266, 267) including fine grooves or fine pores formed in an outer circumferential surface of the guide facing the cylinder (140, 240, 240-1, 240-2) and provided at a position corresponding to the gas inflow passage, characterized in that the plurality of fine irregularities (265, 266, 267) include: a plurality of second fine irregularities recessed from the outer circumferential surface of the guide, extending in a circumferential direction of the guide to have a circular band shape and arranged in an axial direction; and a plurality of first fine irregularities recessed from an inner surface of each of the second fine irregularities and formed to be spaced apart from each other in a circumferential direction of the second fine irregularities. a guide having a cylindrical shape; a head positioned at a front side of the guide; and a plurality of fine irregularities (265, 266, 267) including fine grooves or fine pores formed in an outer circumferential surface of the guide facing the cylinder (140, 240, 240-1, 240-2) and provided at a position corresponding to the gas inflow passage, characterized in that the plurality of fine irregularities (265, 266, 267) include: a plurality of second fine irregularities recessed from the outer circumferential surface of the guide, extending in a circumferential direction of the guide to have a circular band shape and arranged in an axial direction; and a plurality of first fine irregularities recessed from an inner surface of each of the second fine irregularities and formed to be spaced apart from each other in a circumferential direction of the second fine irregularities. a plurality of second fine irregularities recessed from the outer circumferential surface of the guide, extending in a circumferential direction of the guide to have a circular band shape and arranged in an axial direction; and a plurality of first fine irregularities recessed from an inner surface of each of the second fine irregularities and formed to be spaced apart from each other in a circumferential direction of the second fine irregularities.