A sequence-pair creating apparatus includes a block placement storing unit that stores information of size of a block b.sub.i in a block set B and information of block placement, creates a sequence-pair (P, M), serving as a pair of a sequence P and a sequence M of the block b.sub.i, and further includes a binary relation setting unit that sets, in accordance with the information of block placement and information of size, a binary relation serving as an order relation that indicates a relative configuration between the blocks of a block pair of two blocks and that is derived from a configuration constraint between the blocks extracted from the information of block placement and information of size or designated by an external input, and a total order relation setting unit that sets a series of ranks of the sequences P and M for all the blocks on the basis of the information of block placement and information of size so as to satisfy all binary relations set by the binary relation setting unit.