Disclosed is a gas analysis device capable of performing calibration without being influenced by the degradation of a span gas in a span gas supply line, said gas analysis device being provided with an open/close mechanism control unit (61) which accepts a calibration start signal indicating the start of zero calibration and span calibration and controls an open/close mechanism (31) in a span gas flow path (3) and an open/close mechanism (21) in a zero gas flow path (2). The open/close mechanism control unit (61) controls the open/close mechanism (31) in the span gas flow path (3) so that the open/close mechanism (31) in the span gas flow path (3) is opened for a predetermined time before the start of the span calibration when accepting a new calibration start signal after a predetermined time has elapsed since the last calibration, thereby discharging the span gas remaining in the span gas flow path (3).
