A steel wire retainer for a sliding block comprises a plurality of steel wire retaining members, each of which includes a locking section on the sliding block and a plurality of steel wire retaining members. The steel wire retaining members each has a hook formed on the retaining portion thereof for hooking the locking section of the sliding block. The restraining portion of the respective steel wire retaining members will cooperate with the rolling grooves of the sliding block to form a ball rolling path, and the restraining portion of the respective steel wire retaining members is formed with a plurality of reinforced folding portions. The simple, low cost and easily assembled steel wire retaining members have sufficient support strength and are suitable for various sized sliding blocks and can make the linear transmission apparatus operate stably.