The invention provides a communication terminal and a mobile communication system. The mobile communication terminal has a leaky transmission line whose radiation direction faces opposite a radiation direction of a part or a whole of the leaky transmission line of a wireless base station, as at least a part of an antenna element, connected to the communication terminal. Here, preferably, when a difference in angle between the radiation directions falls within the range between 180+-7.5 degrees, the radiation directions are considered to face opposite each other. With this configuration, even when the leaky transmission line of the wireless base station has a curved line portion, a curved portion or the like, it is possible to ensure satisfactory communications with the wireless base station without a complicated configuration of the system but by a simple process to build the system.