Abstract: In a content addressable memory (CAM) where a bit (called a valid bit) indicating whether the data of a word is valid is provided to the word, when the valid bit indicates that the word is invalid, pre-charging is controlled so that pre-charging of the match line of the word may be prohibited. At the same time, the match line is forcibly put into a mismatch state. With this arrangement, the power dissipation for the searching operation at a data word that is not a search object is eliminated, whereby the power dissipation for the operation of searching the entire CAM is reduced. Thus, a reduction in the average power dissipation for a CAM searching operation is achieved without having any influence on CAM performance.