In order to solve the environment problem, this writer believes that we need to get to know well someone who had committed himself to protesting against forest destruction. Kumagusu Minakata's protest against the shrine mergers was studied. He is a well known as an ecologist, having committed himself to the protest against the shrine mergers proposed by the Meiji Government; devoting ten years to the protest. This paper analyses the reasons contained in the texts that Minakata wrote to Mitsutar? Shirai, a biologist. From those texts, it can be understood that Minakata realized that shrine and forest are inseparably one being. He believed that the forest has mystery and is the source of man's life. It was concluded that Minakata's behavior against the shrine mergers was totally “Green Conservation Behavior”. Because of that understanding, he committed himself to conserve the forest and to protest against the shrine mergers.