A foldable enclosure apparatus for a baby bed has a hub device, a supporting assembly and four linking devices. The hub device has four racks. The supporting assembly is disposed around the hub device. Each linking device is connected with the hub device and the supporting assembly. Each linking device has a first linking assembly and a second linking assembly. The hub device is pulled and the racks are moved upwardly. The first linking assemblies and the supporting assembly are moved toward the hub device. The installment of the first linking assemblies and the second linking assemblies has the effects of linkage and balance. Therefore, the foldable enclosure apparatus for a baby bed can be easily, smoothly and steadily folded and spread.