a header portion of the packet to obtain the size of the data and calculates an accumulated value of the amount of transmission data in step s 803 the communication monitoring unit 301 determines whether or not the accumulated value of the amount of transmission data is greater than or equal to a threshold value when the accumulated value of the amount of transmission data becomes greater than or equal to the threshold value in step s 804 the communication monitoring unit 301 sets the u201c maintaining connection u201d in the operation management information as the out of service operation in this case it is assumed that the accumulated value of the amount of transmission data becomes greater than or equal to the threshold value in this way if the accumulated value of the amount of transmission data is greater than or equal to the threshold value as out of service operation it is possible to perform the restoration processing of the connection in the link layer while maintaining the logical connection of the application as described above according to the third embodiment when an application for transmitting data is executed it is possible to set the out of service operation or the connection maintaining time on the basis of the size of transmitted data or a progress state of transmission of the transmission data or the reception data next a mobile station 4 according to a fourth embodiment will be described in the fourth embodiment if a plurality of applications are executed when out of service is detected an out of service operation is determined for each application fig1 is a block diagram illustrating an example of functions of the mobile station 4 according to the fourth embodiment in the functions illustrated.