A sliding door apparatus has a sliding door movably supported on a horizontal door rail for opening and closing an entrance of a vehicle, i.e. railroad car. The sliding door is locked when a latch member engages a fixing member disposed on the sliding door. When an emergency handle is operated, the latch member is released from the fixing member, and the sliding door can be opened manually. A motion of the emergency handle is directly transmitted to the latch member to release the latch member from the fixing member. Therefore, it is possible to operate the sliding door reliably without a problem associated with the flexible wire.