The purpose of this article is to develop a method to analyze characteristics of land use agglomeration using grid data in a small area. To this end, the behavior of a criterion called as Same Edge Ratio (SER), which is the average ratio of edges of each grid connected with the same kind of land use, is analyzed. First, its expected value in a small torus area of binomial distribution land use pattern is calculated. Second, the cause of its difference from the binomial probability is clarified. Last, an estimation method of the binomial probability based on SER is proposed.