A verification method is provided for verifying a safety apparatus including a programmable logic device having a plurality of functional elements. The verification method includes the steps of exhaustively verifying the plurality of functional elements on actual hardware, generating a functional element that is the same as one of the functional elements verified on the actual apparatus using a predetermined hardware description language, independently logic-synthesizing each generated functional element into a plurality of first net lists, generating a connection function between the functional elements using the predetermined hardware description language, logic-synthesizing the generated connection function into a second net list corresponding to the connection function, synthesizing the first net lists with the second net list to generate a third net list, writing a logic circuit into the programmable logic device on the basis of the third net list, and verifying the actual programmable logic device.