The heat developing apparatus heats and conveys a film with a heat developing photosensitive material coated on one side of a supporting substrate and makes a latent image formed on the film visible, which includes a first zone composed of stationary guides 51b and 52b having a heater and opposing rollers 51a and 52a for pressing the film against the stationary guides and a second zone 53 composed of a stationary guide 53b having a heater and another guide 53a forming a predetermined guide gap with the stationary guide, wherein the guide gap of the second zone is 3 mm or less.