A direction detecting apparatus provided at a known position from a lower end of a supporting pole, comprising an image pickup device with an optical axis orthogonal to an axis of the supporting pole and an arithmetic processing part for calculating based on an image from the image pickup device, wherein the image pickup device acquires an image so as to include an object for which a direction is to be detected, wherein the arithmetic processing part calculates and detects a direction and a tilt of the object from a relation between a position of the object in the image and an optical axis of the image pickup device.