A multistage lock apparatus has a base, a disk holder, two selecting devices, two disk sets and at least one interfering element. The base has a mounting panel and a central tube. The disk holder is connected to the base and has a mounting beam, two extending beams, a middle beam, a connecting beam and two mounting spaces. The selecting devices are rotatably connected to the base. The disk sets are respectively mounted on the selecting devices in the mounting specs of the disk holder and each disk set has a driving disk and at least one driven disk. The at least one interfering element is mounted securely on the disk holder and each of the at least one interfering element has a mounting tab and two elastic panels.