According to this load detection method, load (Fi) in insertion of a linear body (2) having flexibility in an inlet of a hollow tube (1) inserted in a bending vessel in a body is detected, an image of the hollow tube (1) or the linear body (2) is taken, a degree of bending of the hollow tube (1) or the linear body (2) is detected based on the image, and load (Fo) at a tip end of the linear body (2) is calculated based on the detected insertion load (Fi) and the degree of bending. Therefore, the load (Fo) at the tip end of the thin linear body (2) can readily be detected.
