Disclosed are a two-agent type disinfectant composition for hard articles, which includes a first agent containing a powder mixture (A) and a second agent containing an aqueous hydrogen peroxide solution (B-1), the powder mixture (A) containing an alkali metal salt (A-1) exhibiting basicity when the salt is in the form of an aqueous solution, a water-soluble copper salt (A-2), a compound (A-3) represented by the following formula (1), and a nonionic surfactant (A-4) represented by the following formula (2), and in which the molar ratio of the water-soluble copper salt (A-2) and the compound (A-3) represented by the mixing amount of (A-3)/mixing amount of (A-2) is 3.0 to 20; and a single-agent type disinfectant composition for hard articles, which includes the components (A-1) to (A-4), and an inorganic peroxide (B-2) that releases hydrogen peroxide in water, and in which the molar ratio of the water-soluble copper salt (A-2) and the compound (A-3) represented by the mixing amount of (A-3)/mixing amount of (A-2) is 3.0 to 20. Disinfectant compositions for hard articles which have high disinfecting power against the surfaces of hard articles, have satisfactory stability of hydrogen peroxide in water, and have low foaming tendency, and a method for disinfecting the surface of a hard article by using the disinfectant composition for hard articles, can be provided.