With the lack of natural materials etc., various "imitation" similar to "real" is used as building finishing materials. Now, it needs to be made clear how similar the imitation is to the real (aimed at). So, it is important to extract the factors that influence the imitativeness of imitation, and to make clear fundamental points for more similarity. First, we investigated visual impressions of the real and the imitation, and the change of visual impressions through several times of observation. Second, we investigated visual judgment of the real or the imitation, and imitativeness of the imitation. Last, we extracted the factors that influence the imitativeness of the imitation, and made clear fundamental points when producing and choosing the imitation more similar to the real.