A search device creates as many stack frames as the number obtained by adding one to the number of search condition character strings contained in an out-of-search-condition character string in a stack, sequentially inputs character strings in a text into automaton data, determines whether the character strings in the text hit the search condition character string or the out-of-search-condition character string to push correspondence to the stack or to change correspondence into non-correspondence, and determines whether the text is to be searched.