Based on the interaction between construction and causative words, this paper explains the reasons for the diversity of causative words in the construction of causative words. This paper refers to Goldberg’s construction diagram and summarizes the interaction schema between the causative construction argument and the actor role of causative words. In this paper, relevant examples are used to explain the principle of the integration of the constructional elements of causative words and the roles of participants in causative words. On the basis of the fusion principle, this paper analyzes how the causative construction chooses and limits the actor role of causative words. This paper also makes a detailed summary of the fusion law between the causative constructors and the participants of causative words.

Benefactive verbs in Japanese can be classified into 1) ‘site ageru’(「してあげる」, 2) ‘site kureru’(「してくれる」), and 3) ‘site morau’(「してもらう」) depending on the direction of action. ‘Site morau’ sentences are syntactically and semantically similar to passive sentences in the sense that a benefactive of an action is in the subjective position and an agent is in the dative position. However, they morphologically take an active form. Thus, they share characteristics of both the active and passive voice. This article investigates the condition in which a ‘site morau’ sentence changes into a causative sentence. In addition, it analyzes the semantic similarities and differences between causative sentences and ‘site morau’ sentences. It also shows that ‘site morau’ sentences can be changed into causative sentences, since causative sentences have semantic properties of both ‘giving’ and ‘receiving’. Lastly, ‘site morau’ is subcategorized into 1) typical ‘site morau’, 2) moderate ‘site morau’, 3) causative ‘site morau’, with each type studied in depth.