A disclosed downlink channel configuration method in a radio communication system includes a step of including a broadcast channel, a paging channel, and a downlink shared channel as transport channels; a step of including as a physical channel a physical downlink shared channel to which the downlink shared channel of the transport channel is mapped; and a step of sharing the downlink shared channel by plural users without using a dedicated channel separately allocated to each of the users. In a preferred embodiment, as the physical channels, there are further included a physical broadcast channel as an independent radio resource to which the broadcast channel of the transport channel is mapped and a physical paging channel as an independent radio resource to which the paging channel of the transport channel is mapped.