The Suzuki-Binet Test includes “ball and search” problem (No.41, 49): such test was used in this study. In study I and II, the performance of the problem with 37 mentally retarded persons was investigated. 20 subjects drew balls at specified spots looking for the balls. 7 out of the 20 drew themselves in addition. Such subjects were found inferior to the related problems concerning reasoning and understanding. In Study III, the same problem was given to 30 normal third graders. They were asked at the end to recall the given instructions. 2 subjects drew balls and 13 searched only partially the inner circles, while their recalls showed a tendency to lack the instruction: “The ball's position should not be determined.” These results indicated that the solution of the problem required not only executing the plan of search well but also understanding the problem adequately. To consider the search itself, logical requirements should be deduced from the instructions. Mentally rerarded persons were considered to be poor at constructing internal representations adapted to the problem demands.