A radio transmitting apparatus and a radio transmitting method wherein the increase of the guard time in a random access region is reduced to secure the data transmitting region of an upstream line. In this apparatus, when a received signal power estimated by a received signal power estimating part (205) is the higher, a RACH format selecting part (206) selects a RACH format having the longer frame length. Contrarily, when a received signal power estimated by the received signal power estimating part (205) is the lower, the RACH format selecting part (206) selects a RACH format having the shorter frame length. A RACH data part arranging part (207) appropriately selects, in accordance with the selected RACH format, top-priority information, such as terminal identifiers, priority information, such as connection request information or band assignment request information, and non-priority information and arranges RACH data parts.