PURPOSE: To recognize a cell head position of its cell, even in the case that an overhead area, etc., intrude into the cell by providing a means for counting the length of an overhead and a cell head predicting means.

CONSTITUTION: With regard to a receiving signal, a counting mean 63 assumes repeatedly plural headers in which plural continuous phases are the heads, respectively and counts the length of an overhead which intrudes into those virtual headers, respectively. A cell head predicting means 64 selects a genuine header from plural virtual headers, based on a header recognition timing by a header recognizing means 62, considers fixed length of the header for the overhead length of its header and recognizes the header length of the cell, and generates a cell head signal by a timing by which the cell head is outputted from a delay buffer 61, based on its result. Also, a cell length counting means 65 counts a cell fixed length part, with the cell head signal from the predicting means 64 as a reference, and outputs the cell head signal by the cell head of the cell which next follows.