To solve the problem in a conventional technique that useless cell search when a mobile radio terminal device is in a stationary state increases power consumption or that a cell cannot be searched in both of two mobile radio systems, if cell search is applied to a dual system because a single system is an object.

The mobile radio terminal device has a 2G control section and a 3G control section, obtains an index Nr indicating frequency of shifting of a cell obtained from the 2G control section and a reception electric field strength Rx_Lev of a 2G cell when deciding the period of 3G cell search, and thereby deciding a cell search period T_3G of 3G by referring to a table stored in a main body storage section 16 (steps S3, S4). When it is determined by the index Nr that the mobile radio terminal is in a stationary state, the cell search period of 3G is set at a long period, thereby enabling suppressing useless cell search at the time of stationary state. When it is determined that the terminal is moving, the cell search period of 3G is set at a short period.