Patent ID: 7840583

Claim:
A search device comprising: a storage unit storing a plurality of file information items that respectively identify a plurality of files, the plurality of files each including one or more character strings, a character string list that includes one or more character strings and one or more identification numbers, the one or more character strings being included in at least one of the plurality of files, and the one or more identification numbers respectively uniquely specifying the one or more character strings, and a presence/absence information list that includes presence/absence information blocks respectively for the plurality of files, the presence/absence information blocks each expressing one or more presence/absence information items which respectively indicate presence or absence relative to the one or more character strings included in the character string list, and the one or more presence/absence information items being arranged in an order dependent on the one or more identification numbers; an obtaining unit that obtains a search character string as a search target to be searched for; an identification number specification unit that, when a character string including the search character string obtained by the obtaining unit is included in the character string list, specifies an identification number uniquely specifying the character string from the character string list; a file specification unit that specifies a file including the character string uniquely specified by the identification number specified by the identification number specification unit, in accordance with the one or more presence/absence information items in the presence/absence information list; and an output unit that outputs one of the plurality of file information items which indicates the file specified by the file specification unit.