Random access technology is provided for establishing an individual channel between a radio communication terminal device and a base station device in a short time and a radio communication terminal device executing the random access method. A RACH sub-channel allocation unit allocates a transmission packet input from a replication unit to an arbitrary sub-carrier at the RACH arbitrary time slot at random. An allocation unit judges whether an overlap is generated in the allocation result obtained by the RACH sub-channel allocation unit.