To correct dead time in TOF experiments with multi-detector gamma-ray detection method, we have tested a dead-time correction method. In this dead-time correction method, random timing pulses generated by a random pulse generator are input to every pre-amplifier via test-signal inputs. Both the random timing pulses and the other pulses originated from gamma rays are measured with a data acquisition system (DAQ). At the same time, a number of the input random timing pulses are counted with another fast system. Because dead time affects similarly both the pulses from the random pulse generator and the measured gamma rays, we can calculate the dead time by comparing the number of the input random timing pulses counted by the fast system with an area count of the peak due to the random timing pulses measured with the DAQ.