We analyzed a printing method using direct toner transfer by a light flash in which the image-forming process was expected to be considerably simplified. First, we found the transferred amount of toner particles increased linearly with the irradiated energy and abruptly decreased at long pulse length. Next, we observed the toner movement using a high-speed camera and measured the transmissivity and current transition to clarify the toner transfer process. The toner transfer was caused by a thermal event, and from a temperature simulation we concluded was the ablation of toner occured. Comparison of experiment and simulation results showed the toner transfer started at the time when the inside maximum temperature reached a specific temperature, i.e., the decomposition temperature of the toner material.