A variable throat device for an air compressor, comprising: an air suction pipe for guiding a flow of air at atmospheric pressure into a compressor, a variable throat disposed in said air suction pipe and having a variable diameter of the air suction pipe pressed by an external force to a streamline shape in order to reduce an unsteady flow of air while securing reliable flow control, the variable throat comprising: a plurality of main wings (210, 220, 230, 240, 250, 260, 270, 280) arranged along a circular trace to overlap each other such that a degree of overlap between the main wings is changed by external force to have a variable diameter, each of the main wings having elasticity and being connected at one side or opposite sides thereof to the air suction pipe in an axial direction; and a plurality of main fastening mechanisms each fastening adjacent main wings to allow the degree of overlap between the main wings to be changed, characterized in that each of the main fastening mechanisms comprises: an elongated slot circumferentially formed at the other side of each of the main wings (210, 220, 230, 240, 250, 260, 270, 280); a hole formed at one side of each of the main wings (210, 220, 230, 240, 250, 260, 270, 280) along the same circumferential trace as that of the slot; and a fastening pin fastening the slot of one main wing to the hole of another main wing adjacent the one main wing, so that the adjacent main wings overlap each other by a movable range of the fastener. an air suction pipe for guiding a flow of air at atmospheric pressure into a compressor, a variable throat disposed in said air suction pipe and having a variable diameter of the air suction pipe pressed by an external force to a streamline shape in order to reduce an unsteady flow of air while securing reliable flow control, the variable throat comprising: a plurality of main wings (210, 220, 230, 240, 250, 260, 270, 280) arranged along a circular trace to overlap each other such that a degree of overlap between the main wings is changed by external force to have a variable diameter, each of the main wings having elasticity and being connected at one side or opposite sides thereof to the air suction pipe in an axial direction; and a plurality of main fastening mechanisms each fastening adjacent main wings to allow the degree of overlap between the main wings to be changed, a plurality of main wings (210, 220, 230, 240, 250, 260, 270, 280) arranged along a circular trace to overlap each other such that a degree of overlap between the main wings is changed by external force to have a variable diameter, each of the main wings having elasticity and being connected at one side or opposite sides thereof to the air suction pipe in an axial direction; and a plurality of main fastening mechanisms each fastening adjacent main wings to allow the degree of overlap between the main wings to be changed, an elongated slot circumferentially formed at the other side of each of the main wings (210, 220, 230, 240, 250, 260, 270, 280); a hole formed at one side of each of the main wings (210, 220, 230, 240, 250, 260, 270, 280) along the same circumferential trace as that of the slot; and a fastening pin fastening the slot of one main wing to the hole of another main wing adjacent the one main wing, so that the adjacent main wings overlap each other by a movable range of the fastener.