Frege's puzzle concerning belief reports has been in the middle of the discussion on semantics and pragmatics of attitude reports: The intuition behind the opacity does not seem to be consistent with the thesis of semantic innocence according to which the semantic value of proper names is nothing but their referent. Main tasks of this book include providing truth-conditional content of belief reports. Especially, the focus is on semantic values of proper names. The key aim is to extend Crimmins's basic idea of semantic pretense and the introduction of pleonastic entities proposed by Schiffer. They enable us to capture Frege's puzzle in the analysis without giving up semantic innocence. To reach this conclusion, two issues are established. First, based on linguistic evidence, the frame of belief reports functions adverbially rather than relationally. Second, the belief ascriptions, on which each belief report is made, must be analyzed in terms of the measurement-theoretic analogy.