A posture sensing alert apparatus is provided. The posture sensing alert apparatus comprises an attachment element, a detecting element, a processing element and an alert element. The attachment element is adapted to attach on a human body. The detecting element is disposed on the attachment element and is adapted to sense a posture change from the human body. The processing element is disposed on the attachment element and connects to the detecting element. The processing element is adapted to output a signal to the alert element in response to the posture change for a predetermined period so that the alert element is adapted to output an alert accordingly.