A data storage device includes a storage module, a casing, a sliding member, and an elastic member. The storage module has a plurality of pins and memory units electrically interconnected. The casing includes a base, three sidewall members, a support member, a first abutting portion, and an accommodating region defined cooperatively by the sidewall members. At least one guide block is disposed on each of the oppositely arranged sidewall members. The first abutting portion is formed on one side of the support member. The sliding member has a second abutting portion and at least one guide rail corresponding to its respective guide block. The support member is arranged between the sliding member and the base. The elastic member is held by the first and second abutting portions on opposite ends thereof The compression and restoration of the elastic member allows the sliding member to selectively conceal the pins.