A computer-readable recording medium stores a design support program causing a computer to perform: detecting a data path and a clock path corresponding to the data path making up a partial circuit in a circuit-under-design; selecting an object cell from cells on the data path and the clock path detected in the detecting; replacing the object cell selected in the selecting with a cell having a function substantially identical to and characteristics different from the object cell; acquiring a plurality of types of characteristic information related to the partial circuit based on the data path and the clock path after the object cell is replaced in the replacing; determining whether the types of the characteristic information acquired in the acquiring is in violation of restrictions; and outputting a determination result determined in the determining.