The purpose of the present invention is to improve evaluation accuracy of a photographed image when an event occurs. An image evaluation method according to the present invention includes steps, which are carried out by a server, for: storing, in a plurality of storage units, organism images each corresponding to a mode of an organism and outbreak environment information indicating the range of environment information suited for a mode of an organism; receiving a photographed image transmitted from a portable terminal; receiving environment information measured by a sensor terminal from the sensor terminal; retrieving organism images similar to the received photographed image among a plurality of organism images and assigning scores to names each related to the mode of an organism corresponding to the retrieved organism image; extracting names each related to the mode of an organism associated with outbreak environment information including the environment information received from the sensor terminal; assigning a weight to the scores of the extracted names; and transmitting a name, having the highest score among the plurality of scores as an evaluation result name, to the portable terminal that has transmitted the photographed image.