A circuit board analyzing method and a circuit board analyzer are provided which can greatly reduce analyzing time. The circuit board analyzer includes a computing unit 110, a memory unit 140 connected to the computing unit 110, and an input unit 160 connected to the computing unit 110. The computing unit 110 includes a wiring data acquiring section 310 acquiring data of wirings formed on a circuit board, a basic circuit diagram forming section 320 dividing the wirings into meshes and setting cells and branches connecting the adjacent cells, and an interference analysis setting section 330 setting an element ignoring range of elements set in the cells and the branches.