To provide a waveform determining apparatus which can perform appropriate pass/fail decision on a signal waveform, even if there is superposition of noise on the signal waveform or if there are slight fluctuations in the signal waveform.

The waveform decision apparatus comprises a measurement section for measuring an input signal, at a predetermined cycle to output a measured value and a control section which displays a signal waveform WS, on the basis of the measured value and an allowable range (an allowable range image F) for the signal waveform WS on a display section 5 and performs pass/fail decision processing on the signal waveform WS, on the basis of the signal waveform WS and the allowable range image F. The control section decides that the signal waveform WS is outside the allowable range image F, when a period of a part in the signal waveform being outside the allowable range image F exceeds the allowed period and decides that the signal waveform WS is not outside the allowable range image F, when the period of the part is not greater than the allowed period.

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