A method for solving an optimization problem includes: causing a cylindrical algebraic decomposition (CAD) processing unit to carry out a projection processing for a first expression that appears in a quantifier elimination problem equivalent to the optimization problem including objective functions and to generate second expressions that are projection factors of the first expression; calculating plural sets of values of the objective functions by generating plural value sets of variables in the objective functions and substituting the generated plural value sets of the variables into the objective functions; extracting points including non-dominated solutions in a space mapped by the objective functions, from plural points corresponding to the plural sets of values; calculating, for each second expression, an evaluation value concerning a distance between a corresponding second expression and each of the extracted points; and identifying a second expression whose evaluation value is minimum.