A keyboard device for an electronic keyboard instrument, capable of ensuring stable contact between movable contacts and fixed contacts of a switch body, to accurately detect key depression information. A hammer has a pressure-applying surface formed in a predetermined configuration. A key switch detects key depression information and includes a substrate with fixed contacts, a hollow switch body with a pressure-receiving surface, and movable contacts provided inside the body. Pressing of the pressure-receiving surface by the pressure-applying surface sequentially brings the movable contacts into contact with the fixed contacts, causing switch body compressive deformation. The pressure-receiving surface and pressure-applying surface are complementary in shape, and an orientation of the former conforms to an orientation of the latter when hammer pivotal motion is terminated after the movable contacts are brought into contact with the fixed contacts.