It is proposed in Inoue(2001,2004) that there are two kinds of empty categories distinguished in conceptual structure. That is to say, (1)α, β, γ ... and (ii)φ. The former is like PROobl in that it obligatorily requires an antecedent. The latter, on the other hand, is like PROarb in that it requires no specific reference. The purpose of this paper is to explore the properties of obligatory control on semantic representation for the former category and the relationship of the former to the systactic obligatory control PROobl. The main questions to be addressed here for the theory of obligatory control are the following : (1)What is the semantic status of the controller? (2)What is the semantic status of the controlled element and what relationships hold bewween the controller and controlled element? (3)Is it possible for one controller to allow more than one controlled element? (4)Does the semantic obligatory control correspond to the syntactic conterpart, or vice versa? Questions (1) to (3) are investigated on the basis of the analyses of various kinds of English verbs made in Inoue(2001) as well as in Inoue(2004). The last question is investigated in terms of the conceptual structures for verbs force and promise with to-infinitive complements. It is suggested through these investigations that obligatory control phenomena on syntactic representation constitute a subset of those phenomena on semantic representation.