A waveform analyzer includes a converter which converts a logical function, where a pair of data including a time and a value at the time is variable, created according to data sets of a time and a value of a signal waveform at the time into a second function expressed by a binary decision diagram, an acquisition unit which obtains for each of characteristic points of a reference waveform a condition representative of constraints on a relationship between time information specified by the points and a value corresponding to the time information in the signal waveform according to a value of the reference waveform at the points and a specified tolerance given to a value of the reference waveform, and a searching unit which applies the condition for each of the points to the second function to obtain a time range which meets the entirety of the conditions.