Provided is an apparatus for inspecting a structure including a heating tube, a tube sheet supporting the heating tube, and a flow distribution baffle, which are installed in a steam generator of a nuclear power plant, and more particularly, an apparatus for visually inspecting and removing a foreign object in gaps of a bundle of heating tubes of an upper portion of a tube sheet of a secondary side of a steam generator, in which a detector is inserted into gaps of a bundle of heating tubes of an upper portion of a secondary side of a steam generator so as to inspect sludge or foreign objects, and a foreign object remover removes foreign objects when foreign objects are discovered in the gaps of the heating tubes.