A slide rail apparatus includes an outer rail, an intermediate rail, an inner rail, a latch member slidably mounted to the intermediate rail, and a resilient member. The latch member includes a first abutting post and a second abutting post. When the supporting member supports the first abutting post to keep the latch member at a locking position, the second abutting post of the latch member abuts a stop portion of the intermediate rail, to slide the intermediate rail and the inner rail forward synchronously. When the latch member slides forward to be received in a positioning notch of the outer rail, the resilient member restores to slide the latch member to an unlocking position, where the second abutting post of the latch member disengages from the stop portion, to enable the inner rail to slide out of the intermediate rail.