1. A method of searching a nucleic acid sequence, the method comprising: comparing a reference nucleic acid sequence with a subject nucleic acid sequence to be encoded, converting the subject sequence into a string of characters according to a conversion rule, and compressing the subject sequence by using the converted string of characters; setting an index position of a position of the reference sequence corresponding to a position in the compressed subject sequence, and creating an index correlating reference sequence index position with compressed subject sequence position; receiving an input query regarding DNA information at a position of the subject sequence, and searching for the position in the converted string of characters by using the created index; and converting a character found at the position into a sequence according to the conversion rule, and outputting the sequence as a response to the query.