In a body position detecting apparatus, a controller repeatedly acquires image data that includes an object and an operator in a place where the operator is capable of operating the object. When the controller detects that the operator is in an operating position where the operator operates the object, the controller detects a position of a body part of the operator in the image data and the controller sets the position of the body part to an initial position. The controller detects a position of the body part of the operator in the image data that is acquired after the initial position is set, by detecting a displacement from a position of the body part detected last time and accumulating the displacement to the initial position.