An image-related information displaying system includes: a host system having a three-dimensional land feature/place name information database and a delivery service subscriber list database; and multiple mobile terminal devices, each of which receives land feature/place name information from the host system and is connected to a base station via respective radio channels The base station is connected to a network, such as a wired public telephone circuit network, and the host system is connected thereto. Individual mobile terminal devices and the host system are bilaterally connected via the radio channels and the network which both reach to the base station. The base station corresponds to a base station managed by a cellular phone service provider when cellular phones are used as radio transmitter-receiver means. The host system includes the three-dimensional land feature/place name information database and the delivery service subscriber list database. Data on three-dimensional coordinates of representative points which represent land features, for example, throughout Japan, and the corresponding name and information are registered in the three-dimensional land feature/place name information database in the host system. The host system includes a retrieval processor unit for performing a process of retrieving land feature information from the three-dimensional land feature/place name information database in response to a request for the land feature information from one of the mobile terminal devices, and a transmitter-receiver unit for transmitting and receiving data between the host system and each of the mobile terminal devices.