The present paper is concerned with educational psychological researches dealing with cognitive style. Cognitive style is conceptualized as individual difference in accepting and processing of informations. But this concept cannot be defined simply. The definitions range from perceptual level to complex social information processing level. This review is concerned with nine cognitive styles. The purposes of the precsent paper are as follows: 1) Definitions and concepts of cognitive style 2) Methodological definitions and their test methods 3) Relationship between cognitive styles and other intellectual functions, learning behavior, personality and academic performance 4) interactional relationship among cognitive styles 5) Relationship between cognitive styles and educational (instructional) materials and methods The contents provided here are as follows: I. Field-independency vs field-dependency (by Y. Ise) II. Perceptual-motor dominance vs conceptual dominance; flexible control vs constricted control by Stoop-color-word-test (by K. Takagi) III. Reflectivity vs impulsivity (by Y. Kobayashi) IV. Analytic vs non-analytic cognitive style (by Y. Kobayashi) V. Cognitive complexity vs simplicity; integrated complexity vs simplicity ; preference for complexity vs simplicity (by Y. Kobayashi) VI. Cognitive preference (by M. Sawada) VII. Cognitive style and instructional-learning strategy (by K. Kamioka) VIII. Summary and perspection (by M. Sawada)