To provide a thermal developing device which can achieve a desired temperature profile (upward profile and downward profile) and is especially effective in quick heat developing.

The thermal developing device 40 has heat developing sections 51, 52, 53, and 21 incorporating heaters 51c, 52c, 53c, and 23 to heat a film F having latent images from the temperature to form latent images to the heat developing temperature, and a controller to control the heaters. The controller controls the heater based on the sensible heat and the latent heat of the film.