To provide a transmission method in a multiple access radio communication system having orthogonal transmission resources, wherein the number of users can be increased without reducing transmission rates while suppressing interference caused by a shared resource.

In the case that the number M of users is in excess of the number N of transmission resources of the system, at least two users share at least one of transmission resources (s1,..., s8) at a prescribed moment. The users sharing the same resource change with time so that the deterioration of the S/N caused by the resource sharing by the users can be distributed among a plurality of the users (u1,..., u9) as uniformly as possible, and signals transmitted by users sharing the same resource at a prescribed moment are distinguished by their transmission levels so as to further reduce deterioration in the S/N.