Abstract: An operation support system in a component mounting apparatus on a manufacturing line for manufacturing printed board units, comprises: an ID reading unit that reads out cassette identification information for identifying cassettes and component identification information for identifying components from the cassette each comprising tags for recording the cassette identification information and tags for recording the component identification information, wherein at least one reels are loaded on each cassette and tapes to which the components are attached are wound around the reels, and the components are contained in the reels accommodated in the cassettes; a storage unit that stores information for specifying the components previously set to be loaded on the cassettes; and a component loading checking unit that checks whether or not the components loaded on the cassettes are correct by comparing the component identification information with the specifying information corresponding to the cassette identificati