PURPOSE: To provide a received command retrieving device and a retrieval method for the same capable of retrieving efficiently a received command.

CONSTITUTION: The command constituted of characters consisting of bit strings is received, and the corresponding command is retrieved from among the received commands. In this received command retrieving device, a receiving means 8 to fetch the received command and a collation information generating means 22 to generate collation information from the bit strings of the characters to express the received command are provided. Besides, a storage means 81 to store the table of all the commands classified into a command group for every collation information and a first retrieving means 8 to retrieve the collation information of the storage means from the generated collation information are provided. Further, a second retrieving means 8 to retrieve the same command as the received command from among the command group belonging to the collation information retrieved by the first retrieving means is provided.