This paper addresses a diachronic study on the grammatical status of ``malda``. ``malda`` in modern Korean has shown a little attention on the grammatical category as a result of grammaticalization. This present study is an analysis of ``malda`` within ``grammatical category`` and its diachronic changes in historical corpus. The grammatical category of ``malda`` was ``middle verb`` in middle Korean. Middle verb has usages of transitive verb and intransitive verb, and in diachronic change middle verbs were divided into transitive verb and intransitive verb by morphological changes. ``malda`` was not separated into transitive verb and intransitive verb but becames grammaticalized. This change occurred especially during the period of 18C to the early part of 20C. A two-pronged approach which are ``grammatical category`` and ``diachronic changes`` takes it as a focal point for solving problems related to ``malda`` in modern Korean.