1. An information processing method for acquiring and outputting information with respect to an element for discriminating a specific sequence in multiple sequence data, comprising: using a specifically programmed computer to perform the steps of: a first step of acquiring alignment data of multiple sequences in a common region as a matrix of which row vectors correspond respectively to the multiple sequences and column vectors correspond respectively to alignment positions; a second step of selecting a specific sequence and removing an element of any other sequences which is different from the element of the specific sequence at the same alignment position; a third step of comparing two column vectors arbitrarily selected from the column vectors each corresponding to the alignment position involved in the removal of an element in the second step and removing an element in one of the two column vectors if the element of the same sequence in the other column vector was removed in the second step; a fourth step of extracting an element which was not removed in the second and third steps and acquiring the extracted element as a candidate for a set of elements capable of discriminating the specific sequence; and a fifth step of comparing one of the two column vectors after subjected to the third step with any other of the column vectors involved in the removal of an element in the second step and removing an element in either one of the compared column vectors, wherein the second to fourth steps are repeated until only one element is left in the either one of the compared column vectors.