A latch mechanism is provided to lock a cover unit to a base unit, which includes a latching member for being slidably installed in the cover unit and a button for being rotatably fixed to the cover unit. The latching member includes a main body and a hook extending from the main body for engaging with the base unit. The button includes a driving surface operatively engagable with the main body of the latching member for cooperatively transforming rotating movement of the button into linear movement of the latching member thereby disengaging the hook from the base unit.