A safety device for a vehicle, comprising: an impulse sensor provided in a vehicle to allow the relevant vehicle to sense an impulse received from an outside; a compressor provided within a vehicle to constitute a refrigeration cycle and to compress a refrigerant; characterized in that a safety valve (100, 200) is provided in the compressor forming a switching unit (120, 220) for selectively bringing an inner space of the compressor in fluid communication with an outside of the compressor, wherein the switching unit (120, 220) is electrically connected to the impulse sensor and is configured to open and discharge refrigerant in the inner space of the compressor out of the compressor when an impulse sensed by the impulse sensor exceeds a predetermined range, wherein the safety valve (100, 200) comprises: a valve housing (110, 210) having an inlet (111, 211) and an outlet (112, 212); a piston valve (120, 220) provided within the valve housing to selectively bring the inlet (111, 211) in fluid communication with the outlet (112, 212); a valve spring (130, 230) provided at a backpressure side of the piston valve (120, 220) to limit the piston valve (120, 220) from being opened; a spacer (140, 240) inserted through the valve housing (110, 210) to adjust an elastic force of the valve spring (130, 230); and a control unit (150, 250) provided at one side of the valve housing (110, 210) to operate the spacer (140, 240), and wherein the control unit comprises: a motor unit configured to receive power from an outside to operate; a stopper provided in the motor unit to restrict or release the movement of the spacer while being moved by the motor unit; and a return spring configured to support the stopper and move the stopper when the stopper is released from the spacer, wherein a valve guide configured to guide the movement of the piston valve is further provided within the valve housing, wherein the valve guide is slidably coupled to the spacer, and wherein surfaces (242, 262) on which the valve guide and the spacer are brought into contact are formed in an inclined manner to move the spacer and the valve guide in an orthogonal direction. an impulse sensor provided in a vehicle to allow the relevant vehicle to sense an impulse received from an outside; a compressor provided within a vehicle to constitute a refrigeration cycle and to compress a refrigerant; characterized in that a safety valve (100, 200) is provided in the compressor forming a switching unit (120, 220) for selectively bringing an inner space of the compressor in fluid communication with an outside of the compressor, wherein the switching unit (120, 220) is electrically connected to the impulse sensor and is configured to open and discharge refrigerant in the inner space of the compressor out of the compressor when an impulse sensed by the impulse sensor exceeds a predetermined range, wherein the safety valve (100, 200) comprises: a valve housing (110, 210) having an inlet (111, 211) and an outlet (112, 212); a piston valve (120, 220) provided within the valve housing to selectively bring the inlet (111, 211) in fluid communication with the outlet (112, 212); a valve spring (130, 230) provided at a backpressure side of the piston valve (120, 220) to limit the piston valve (120, 220) from being opened; a spacer (140, 240) inserted through the valve housing (110, 210) to adjust an elastic force of the valve spring (130, 230); and a control unit (150, 250) provided at one side of the valve housing (110, 210) to operate the spacer (140, 240), and a valve housing (110, 210) having an inlet (111, 211) and an outlet (112, 212); a piston valve (120, 220) provided within the valve housing to selectively bring the inlet (111, 211) in fluid communication with the outlet (112, 212); a valve spring (130, 230) provided at a backpressure side of the piston valve (120, 220) to limit the piston valve (120, 220) from being opened; a spacer (140, 240) inserted through the valve housing (110, 210) to adjust an elastic force of the valve spring (130, 230); and a control unit (150, 250) provided at one side of the valve housing (110, 210) to operate the spacer (140, 240), and wherein the control unit comprises: a motor unit configured to receive power from an outside to operate; a stopper provided in the motor unit to restrict or release the movement of the spacer while being moved by the motor unit; and a return spring configured to support the stopper and move the stopper when the stopper is released from the spacer, a motor unit configured to receive power from an outside to operate; a stopper provided in the motor unit to restrict or release the movement of the spacer while being moved by the motor unit; and a return spring configured to support the stopper and move the stopper when the stopper is released from the spacer, wherein a valve guide configured to guide the movement of the piston valve is further provided within the valve housing, wherein the valve guide is slidably coupled to the spacer, and wherein surfaces (242, 262) on which the valve guide and the spacer are brought into contact are formed in an inclined manner to move the spacer and the valve guide in an orthogonal direction.