A content addressable memory (CAM) having reduced power consumption. A storage circuit (23) stores a plurality of patterns of information indicative of which memory word blocks 20-1 to 20-m to activate. If specification information for specifying a predetermined pattern from among the plurality of patterns of information which are stored in the storage circuit (23) is input, an activation circuit (21) activates each content addressable memory word block (20-1 to 20-m) according to a specified pattern. If data to be retrieved is input, a specification circuit (22) specifies a content addressable memory word (20-1-) which has stored data corresponding to the data to be retrieved from among a group (block or blocks) of content addressable memory words (20-1-1 to 20-1-N) activated by the activation circuit (21). As a result, activation will be performed by the content addressable memory word block (20-1). Therefore, by activating only necessary content addressable memory words (20-1-), consumption of power can be reduced.