A lockable case includes a base casing having two opposite first lateral walls, a top cover openably connected to the base casing, a slide block, and two slide bars disposed respectively on two opposite sides of the slide block. Each slide bar has an inner end, and a locking element to engage a corresponding first lateral wall. The slide block is disposed between the inner ends of the slide bars, and is movable between locking and unlocking positions that respectively prevents and permits inward movement of the slide bars. An actuating lever is connected pivotally to the slide block to move the slide block to the locking position. An elastic member is provided for biasing the slide block toward the unlocking position.