A key input apparatus includes a key top capable of moving up and down through a pressing operation; a first substrate, which includes a first surface, which is positioned on the key top side, and a second surface, which is opposite to the first surface, and the first substrate supports the key top and is provided to be movable up and down along with the key top; a second substrate, which is provided between the key top and the first substrate in the direction of the up-and-down movement of the key top, and the second substrate includes a first surface, which is positioned on the first substrate side, and a second surface, which is opposite to the first surface; a magnetic field generation unit; a magnetic sensor unit, which includes a magnetic detection element that detects a magnetic field generated from the magnetic field generation unit; and an adhesion unit, which includes a soft magnetic material capable of adhering to the magnetic field generation unit. The magnetic sensor unit and the adhesion unit are provided on one of the first surface of the first substrate and the first surface of the second substrate, and the magnetic field generation unit is provided on the other of the first surface of the first substrate and the first surface of the second substrate, opposite to the adhesion unit.