A mobile station adapted to communicate with a base station (11a, 11b), the mobile station comprising: a distance calculation unit adapted to calculate a distance between the mobile station itself based on its current position and the base station; a reception power measurement unit adapted to measure a reception power of a reception signal received from the base station; a transmission-path state determination unit adapted to determine a transmission-path quality on a basis of a reception-power theoretical value corresponding to the distance, and a reception power of a reception signal received from the base station, measured by the reception power measurement unit, and to select a communication parameter on the basis of the determined transmission-path quality; and a transmission processing unit adapted to generate a transmission signal to be transmitted to the base station by using the communication parameter selected by the transmission-path state determination unit, wherein the transmission-path state determination unit is further adapted to retain, as candidates of the communication parameter, a first parameter, and a second parameter that is a parameter for performing communication capable of achieving a longer communication distance at a lower transmission speed than for communicating by using the first parameter, to determine presence of rainfall, to receive a notification from a control station, the notification being about a maximum rainy-weather communication area; and to perform a parameter selection by selecting the first parameter as the communication parameter when it is determined that there is no rainfall, by selecting the second parameter as the communication parameter when it is determined that there is rainfall, and by selecting the first parameter at the timing of the mobile station getting from the inside of the maximum rainy-weather communication area to the outside of the maximum rainy-weather communication area; and the maximum rainy-weather communication area is an area in which communication with the base station is possible with a maximum transmission speed when there is rainfall with an assumed maximum quantity of rain. a distance calculation unit adapted to calculate a distance between the mobile station itself based on its current position and the base station; a reception power measurement unit adapted to measure a reception power of a reception signal received from the base station; a transmission-path state determination unit adapted to determine a transmission-path quality on a basis of a reception-power theoretical value corresponding to the distance, and a reception power of a reception signal received from the base station, measured by the reception power measurement unit, and to select a communication parameter on the basis of the determined transmission-path quality; and a transmission processing unit adapted to generate a transmission signal to be transmitted to the base station by using the communication parameter selected by the transmission-path state determination unit, wherein the transmission-path state determination unit is further adapted to retain, as candidates of the communication parameter, a first parameter, and a second parameter that is a parameter for performing communication capable of achieving a longer communication distance at a lower transmission speed than for communicating by using the first parameter, to determine presence of rainfall, to receive a notification from a control station, the notification being about a maximum rainy-weather communication area; and to perform a parameter selection by selecting the first parameter as the communication parameter when it is determined that there is no rainfall, by selecting the second parameter as the communication parameter when it is determined that there is rainfall, and by selecting the first parameter at the timing of the mobile station getting from the inside of the maximum rainy-weather communication area to the outside of the maximum rainy-weather communication area; and the maximum rainy-weather communication area is an area in which communication with the base station is possible with a maximum transmission speed when there is rainfall with an assumed maximum quantity of rain.