A keyboard apparatus includes: a key disposed to be pivotable with respect to a frame; a hammer assembly disposed to be pivotable in response to pivotal movement of the key; a first member; a second member disposed to be slid and moved on the first member when the hammer assembly pivots in response to pivotal movement of the key; and a third member connected to the first member and configured to guide the second member such that the second member is not located at a distance greater than or equal to a predetermined distance from the first member, the third member having a shape in which a second contact area that is an area of contact between the second member and the third member is less than a first contact area that is an area of contact between the first member and the second member.