To provide a wireless LAN system consisting of terminals and at least one base unit that causes no confusion and collision between users of the terminals about processing of commands issued from the terminals and prevents the users of the terminals from misunderstanding the processed result to be a system failure.

Upon the receipt of a command such as channel revision from any terminal, the base unit 10 discriminates whether or not the command is a contention command disturbing reception of other terminals in a reception state and rejects the command when the command is the contention command and informs the terminal issuing the command about it. However, when the priority of the terminal is higher than the priority of the other terminals in the receiving state or when a prescribed time or over elapses from the command receiving time after the other terminals enter the reception state, the base unit 10 accepts the command and informs the other terminals in the reception state about it.