The CANDLES trigger system is used for the study of Double Beta Decay of 48Ca. The detector of this experiment consists of CaF2 crystals as the sources and the detectors, immersed in the liquid scintillator as a 4π active shield. Because the decay constant of liquid scintillator (∼a few10ns) is a few ten times shorter than that of CaF2 scintillator (∼1μs), if we trigger the signal by the pulse height, the energy threshold of liquid scintillator lights are a few ten times lower than CaF2's one. High counting rate of the liquid scintillator causes dead time. In order to avoid this problem, we have developed a Dual Gate Trigger. In this paper, we describe the trigger system of the CANDLES experiment and its performance.