A foldable table with a table top adapted to be positioned erect when not in use, and to be set in either a horizontal state or a slightly slanted state. The foldable table comprises on each side thereof a locking mechanism contained within a housing. A first click member, a second click member and a locking disc are rotatably mounted in the locking mechanism, and the locking disc is adapted to be locked by engagement with the first click member and the second click member so that any shaking of the table top in either the horizontal state or the slanted state can be effectively prevented. The table top can be folded by disengaging the first and second click members from the locking disc. The setting or folding operation of the table top is conducted by lifting up the outer end of a lock releasing lever attached to the locking mechanism.