At each wireless terminal (10-40), a receiving unit (202) receives a signal transmitted from a wireless base station (1). A signal-to-noise ratio measurement unit (204) measures an S/N of this received signal. In the wireless base station (1), a data amount measurement unit (206) measures the amount of data stored in each buffer (11-41) therein. A maximum stay time measurement unit (208) measures a maximum stay time of packets in each buffer. A classification by maximum stay time unit (210) classifies each wireless terminal based on the maximum stay time. A slot assignment priority order determination unit (212) determines an assignment order of time slots to each wireless terminal based on the classification result in the classification unit, the receiving signal-to-noise ratio, the amount of data, and the maximum stay time.