A supporting apparatus for a crib has two legs and a frame. Each leg has a rack. The frame is moveably mounted between the legs and has a body, two moving seats and two adjustment members. The moving seats are mounted on the body, and the legs are inserted into the moving seats respectively. The adjustment members are mounted on the moving seats respectively and engage with the racks of the legs respectively, and each adjustment member is rotatable and moveable upward and downward along a corresponding one of the racks of the legs. The supporting apparatus can be steplessly adjusted to adjust the height of a bed surface of the crib to improve safety.