1. A program for analyzing an electronic-circuit, wherein said program allows a computer to execute: a circuit-information input step of inputting circuit information including an element model describing an electronic circuit; a changed-circuit detecting step of detecting an electronic circuit using a changed element model in the circuit information; an analysis-necessity deciding step of deciding whether waveform analysis is necessary by comparing a characteristic of an element model before change and a characteristic of the element model after change; and a determination-result processing step of displaying the result of deciding whether waveform analysis is necessary and making an instruction for waveform analysis of the electronic circuit using the element model after change for which it is determined that waveform analysis is necessary to cause the instruction to be executed.