This thesis examines the use of the Japanese causative-benefactive construction in natural spoken data from a Japanese celebrity television talk show. The target construction is -(s)ase-te itadak-u, and the original and literal meaning is to receive permission from a respected party (= a benefactor) to do something beneficial to oneself. Many previous studies claim that this original meaning has become less common, and both the causative and benefactive meanings in the construction are weakening. This study, which employs grammaticalization theory as its theoretical framework, reveals that most examples in the data do not support this claim regarding the weakening of benefactive meaning: although there is no concrete benefactor in these examples, the speakers use the construction to express a clear sense of benefit to themselves, thereby connoting a sense of gratitude. This highly salient use of the construction in this data has the grammaticalized meaning that speakers do something good for themselves which is/becomes possible through the context they are in (e.g. …shashinshū o…das-asete itadai-ta-n-des-u... ‘I [had a chance to] publish a photo book’). This expanded meaning involves particular types of semantic changes to the original meaning: semantic generalization in the meanings of permission and benefactor and semantic persistence in the meaning of benefit. These semantic changes are accompanied by the development of both subjectivity and intersubjectivity. Subjectification involves a modality change from deontic permission in the original meaning to epistemic possibility in the expanded meaning. Intersubjectification is observed in a change of honorific type from Humble honorific type 1 in the original meaning to Humble honorific type 2 in the expanded meaning. These changes are considered in light of the nature of television talk-show discourse; the study claims that speakers utilize the expanded meaning to construct a public persona of humility and gratitude.