A data access method for writing data into a storage apparatus is provided, wherein the storage apparatus has a storage unit, the storage unit has a partition, the storage property of the partition is set as a write protect mode and the storage apparatus is coupled to a host system having an operation system. The data access method includes transmitting a command from the host system to the storage apparatus through a human interface device path and setting the storage property of the first partition as a writable mode in response the command. The data access method also includes storing data into the partition by using built-in commands of the operation system. Accordingly, the data access method can write data into a partition that has been at the write protect mode when a user logins the operation system with a limited user authority mode.