The objective of this research is 1) to define the meaning of a “Performance of Good Situational Decision-Making” in baseball considering The Scene, The Circumstances and The Object. 2) To consider the association between “Performance of Good Situational Decision-Making” in baseball and years of experience. The subjects were divided into two groups, one of 322 university students who belong to the All-Japan University Baseball Federation, and the other of 197 high school students who belong to the Japan High School Baseball Federation. Prior to the investigation, we carried out a descriptive survey of 35 coaches of baseball who coach junior high students up to university students, to elicit their ideas of how to play “Performance of Good Situational Decision-Making” in baseball. As a result, 5 items from 9 factors (The Scene for defense・batting・running, The Circumstances for difference in points, count and inning, The Object for Internal situation, analysis and external situation) were chosen and a questionnaire of 45 items was made. As a result, 1) After performing a factor analysis, 9 factors (The Scene for defense, batting and running, The Circumstances for difference in points, count and inning, The Object for Internal situation, analysis and external situation) were extracted. Three scale acted mutually. 2) The university student was superior to a high school student in all factors with the connection with the years of experience. There was no difference between the models of a university student and the high school student for “Performance of Good Situational Decision-Making” in baseball. In a word, “Performance of Good Situational Decision-Making” in baseball is thought to be what a precise play based on it can accomplish under every situation while grasping the necessary information, and predicting it.
