Abstract: A parallel processing designing device includes: an observation point computing section that, in a case in which an order of plural design variables exceeds a predetermined order, eliminates a design variable that has a low contribution to designing, and for each of plural design variables that are less than or equal to the predetermined order, computes plural observation points for searching for a region in which a performance relating to the design variable is executable, by using an acquisition function and a penalty function; a probability distribution computing section that, for each of the plural performances, computes a probability distribution of the performance being executable at the computed plural observation points; and a multiple performance executable region outputting section that outputs, as a multiple performance executable region, an infinite product of the probability distributions that are respectively computed for the plural performances.