The purpose of this study is to develop the criteria for measuring the observation abilities of elementary school students. Object, viewpoint and mental demand constitute the evaluation criteria of observation abilities. Object domain was classified into two- and three-dimensional figures, while viewpoint was classified into constancy and variety of views. Mental demand covered 2 through 5. The assesment tool based on the three-dimensional criteria was developed for the lower, middle and upper grades of 166 elementary school students. Results from this study were as follows. These students` scores were significantly different in the classification by each dimension and distinguishable between the grades. They scored high on two-dimensional figures, constancy of view and lower mental demand, and the upper grade students` scores were higher than the lower ones in all dimensions. Therefore, the evaluation criteria developed in this study can be used effectively for measuring the observation abilities of elementary school students. Implication for this study was determined to be the development of a valid and reliable test for observation abilities of elementary school students.