An object is to provide a suction method and a suction device which depressurize the pressure of the surface of a target installed in an open system to a critical pressure or less and which thereby can suck it and a laser processing device and a laser processing method using these. In a state where a predetermined operating distance is apart from a target installed in an open system and a suction port, the pressure of an inside of a pressure reduction chamber communicating with the suction port is set equal to or less than a critical pressure at which the speed of a gas sucked from the suction port is brought into a critical state; the jet speed of the gas in a jetting port from which the gas is jetted toward the target is set more than a Mach number of 0.2, the Mach number being obtained by dividing a jet speed of the gas by the sound speed of the gas jetted from the jetting port, the gas is jetted from the jetting port and is sucked by the suction port; a swirl flow is formed so as to surround the suction port between the surface of the target and the suction port; and thus the pressure of a central region of the swirl flow from the suction port to the surface of the target is reduced to the critical pressure or less and suction is performed.