1. A computer-readable storage medium storing a specification verification program that causes a computer to perform a specification verification of coverage of a requirements specification of a design object against a design specification of the design object, according to operations comprising: acquiring conditions necessary to be satisfied for execution of each use case from a use case description indicative of the requirements specification of the design object; detecting a state satisfying the conditions acquired in the acquiring, from among a set of states represented in a finite state machine model indicative of the design specification of the design object; determining presence or absence of an undetected state in the set of states in accordance with a result of the detection performed in the detecting; and outputting a result of the determining.