PURPOSE: To realize a high speed search processor in which blocking can be automatically operated, and a blocking overhead can not be generated.

CONSTITUTION: This device is equipped with an input buffer 103 which temporarily stores input data, dictionary 109 which uses an address to a data pattern in the input buffer as an entry, means which registers the address to the data pattern in the dictionary, means which retrieves the dictionary, means 104 which discriminates the validity of the address retrieved from the dictionary, means 105 which collates the data read from the input buffer with the input data, counter 106 corresponding to a repetitive data pattern length, means which updates the counter based on the discriminated result of the validity and the collated result, and means 101 which generates and outputs an output code by the content of the counter and the address to the data pattern.