To provide a receiver for receiving a random access signal, capable of reducing the amount of processing on the reception of a message and further reducing the memory capacity required for reception of the message.

The apparatus comprises a code pattern generation section 101 for generating a code pattern; a correlation value evaluating section 102 for evaluating a correlation value between a preamble reception signal and the code pattern; a preamble delay profile generating section for generating a preamble delay profile based upon the correlation value; a message detection window width memory section 104 for memorizing a message detection window width; a message window position detection section 105 for detecting a message window position, located within the range of a pass timing effective upon the detection of a message, using the preamble delay profile and the message detection window width; and a message pass detecting section 106 for detecting a message pass phase detected as a pass in the detection of a message, using a message receiving signal in the message detecting window.