A formal verification method using an algebraic specification technique is proposed, and its effectiveness is studied. A computerized automatic verification system, which utilizes an algebraic specification to describe system requirements and to prove an inductive theorem based on a term-rewriting technique for verification, is built and evaluated through experimentally verifying the logic design of a digital reactor protection system in boiling water reactors. The results show that the proposed method can mathematically correctly verify the logic design in a limited time, thereby improving accuracy and reducing person-hours for the verification.