A loading mechanism of a storage device for accommodating a hard drive has a loading body and a second supporting arm. The loading body includes a loading base, a first supporting arm extending from one end of the loading base, and an assembling part provided on the loading base. The second supporting arm is laterally and slidably connected to another end of the loading base, and is disposed correspondingly to the first supporting arm. One end of the second supporting arm includes a stand disposed on the loading base and a sliding member disposed on the stand. The sliding member has an elastic engaging part being able to detachably connect to the assembling part. Therefore, the goal of quickly replacing hard disk without using any screws can be achieved.