There are two purposes on this study:(1) To examine the relationship between teacher's leadership behavior and his/her club performance or club member's morale.(2) To examine the influence of situation variables on the leadership effecti veness. Subjects were 313 male and 87 female junior high school teachers. They rated their own leadership, group situation (task characteristics of their club), morale (the rela tion between teacher and students, and the students' attitudes toward practice), and described the records of their club activities during one year. The results were as follows:(1) The relationship between task-oriented leadership behavior (Pbehavior) and club group records were positive. But the relationship between group maintenance (M behavior) behavior and club group records proved negative.(2) Either task-oriented leadership behavior or group maintenance one had close relatio nship with club members' morale.(3) The task characteristics of club had mo derated the relationship between leadership behavior together with club record and club membe rs' morale.