To provide a heat developing apparatus where, though the number of parts can be reduced and its miniaturization can be attained, the unevenness in concentration is suppressed, and a film sheet can be stably carried.

The heat developing apparatus is provided with: a first zone 50 composed of fixed guides 51b, 52b having a heater 51c and counter rollers 51a, 52a pressing a film toward the fixed guides; a second zone 53 composed of a curvature guide 53b having a heater 53c and an another curvature guide 53a, and in which a prescribed gap d is formed between the curvature guides; and a cooling means 54 of cooling the film. The film progressing position of each curvature guide in the second zone lies at the position lower than the curvature center P thereof, the carrying direction to the second zone by the counter rollers is made into a separation direction from the center of the curvature guide, and further, the film is guided into the direction opposite to that of gravity via the second zone by the carrying force by the counter rollers. Each curvature guide in the second zone guides the film to the cooling means at the position lower than the curvature center thereof, and visualizes the latent image on the film.