To provide a method with which data are searched at high speed for high-grade routing services in network communications in a comparatively simple configuration.

Search data 230 are collectively inputted and the data are divided into bits and applied to corresponding entry table 211, 212 and 213 to respectively independently implement search operations. When the search data are inputted while dividing a table to be used for the search into groups in advance, a search key is divided as well in accordance with the table, so that searches are independently and in parallel carried out. Without requiring a complicated control algorithm, the high-speed search operation is realized in the comparatively simple configuration.