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.

This paper is research on change of the meaning of the verb which it originally has by the meaning of a complement. The sentence showing transitivity will turn into an objective type reflexive usage sentence, if a body noun comes to an objective complement. If a body noun comes to a dative complement, it will become a dative type reflexive usage sentence, and if a body noun comes to a benefactive complement, it will become a benefactive type reflexive usage sentence. The subdivision of these three types was carried out further. The semantic element which becomes the standard of a classification is [±visibility], [±relativity] and [±resultativity]. Each type can be classified into the further subsort type according to the combination of these meaning element.