A data search device that is provided in a communication apparatus detects a memory area storing data to be transmitted from a memory unit having memory areas defined by IDs allotted to data. The data search device includes: a first flag that is provided for each of the memory areas of the memory unit, and indicate whether the data in the corresponding memory area is updated; a second flag that is provided for each group consisting of a predetermined number of the first flags, and indicates a data update state when at least one set of data in the first flags in the corresponding group indicates an updated state; and a search control unit that detects the memory area storing the data to be transmitted, by searching for the corresponding first flag after detecting the second flag.