The main purpose of this paper is to recast passive constructions with a constraint-based analysis in which passive constructions are separated from active constructions. In general, a constraint-based analysis within the framework of HPSG explains syntactic and semantic phenomena such as passive constructions with types, constraints, and multiple inheritance hierarchy. To explain passive constructions as a separate phenomenon from active constructions, the type of English passives is regarded as the subtype of ergative, and according to Grimshaw (1990) and Wechsler (1995), PP[by] phrase in English passive constructions is considered as an adjunct, not as an optional complement. But there is still a problem that cannot be explained by the established binding theory, when PP[by] phrase is treated as an adjunct. It is necessary to adopt ‘Adverb Addition Schema' of Sag (2005) and ‘Amalgamation of Argument Structures' of Park Hyo-Myong (2006) to solve this problem within the framework of a constraint-based analysis.