The disclosed invention relates to a pulsed iodine laser apparatus. The laser apparatus has a flashlamp-pumped iodine laser oscillator which produces a laser pulse with a full pulse width of longer than 1 microsecond, and a COIL amplifier. The laser apparatus may has a controller which controls the timing of injecting chlorine gas contained in a high-pressure chlorine tank into the singlet oxygen generator by outputting an open/close signal of the valve V2, and the timing of injecting iodine molecules contained in a iodine molecule tank into an amplifier chamber of the COIL amplifier.