Disclosed is a system for correcting a passenger's posture in an autonomous vehicle, wherein the system includes a camera configured to measure a distance between a headrest and a head of the passenger, a plurality of body pressure sensors configured to be uniformly embedded across an entire area of the seat and sense body pressures of the passenger, a pressurizing device configured to be expandably installed inside a seatback and press between T10 and T12 of a thoracic spine of the passenger, and a controller configured to control an operation of the pressurizing device on the basis of the distance measured by the camera and a scapular pressure of the passenger, which is sensed by the plurality of body pressure sensors.