In a wireless base station, when a newly provided control unit receives an IP packet from one mobile station (102), it refers to a destination address in control information added to the IP packet (104), and determines whether the IP packet is one to be broadcast or multicast (106). If the value of destination address is at a value indicative of broadcasting or the like defined by IP, the IP packet is copied according to the subnet, and is sent back to a wireless link layer processor with its contents intact (108). Further, the wireless link layer processor is commanded to broadcast the sent-back IP packet in a wireless area and so forth (110), whereby the IP packet can be broadcast into a cell and so forth.