1. A tire inspection device comprising: a storage means for storing an integer numeric filter generated from an analyzing wavelet that is created for wavelet transformation correlating time corresponding to tire surface position, and frequency, the analyzing wavelet being based on a frequency representing a characteristic portion of a predetermined tire surface structure; a detection means for detecting surface structure of a tire; a transformation means for wavelet transformation of a detection signal from the detection means using a numeric filter as an analyzing wavelet; and an output means for outputting as characteristic information the characteristic portion representing the transformation result of the transformation means.