A hole saw includes an arbor, a saw blade assembly having a saw blade and an adapter connected with the saw blade and provided with a protrusion received in an indentation of the arbor, a lid movably mounted on a body portion of the arbor and movable relative to the arbor between a first position where second coupling portions of the adapter are blocked by a block portion of the lid and coupled to first coupling portions of the arbor such that the saw blade assembly can't be rotatable relative to the arbor, and a second position where the second coupling portions of the adapter are staggered with the block portion and uncoupled from the first coupling portions of the arbor through the rotation of the saw blade assembly. Thus, the hole saw has the advantages of reducing vibration in use and convenience in assembly and disassembly works.