A lock mechanism adapted to an electronic device with a base, a first casing and a second casing includes a sliding member, a push button, a latch member, a first guiding structure and a second guiding structure. The sliding member is disposed on the base in a slidable manner. The push button is combined with the sliding member for driving the sliding member to slide relative to the base. The latch member is disposed on the base in a slidable manner. The first guiding structure is disposed on the sliding member. The second guiding structure is disposed on the latch member. The second guiding structure cooperates with the first guiding structure for sliding relative to the first guiding structure when the sliding member slides relative to the base, so as to guide the latch member to a locking position for locking the first casing and the second casing.