A key switch includes a baseplate, a circuit layer, a keycap and a support rod. The baseplate has a hook and a first through hole neighboring to the hook. The circuit layer includes a plurality of superimposed sublayers disposed above the baseplate and having a through hole structure passing through the sublayers; a portion of one of the sublayers extends in the through hole structure over the first through hole and forms a resilient portion neighboring to the hook. Two sides of the resilient portion connect to the circuit layer. The keycap is disposed above the baseplate and can move upward and downward in respect to the baseplate. The support rod has a first portion, movably connecting to the keycap, and a second portion, engaged with the hook. The resilient portion extends beneath and abuts against the second portion for buffering a collision between the second portion and the baseplate.