A collision detecting structure includes a pressure generating tube extending in a vehicle width direction, a rear wall portion disposed on a rear side of the pressure generating tube, a tube compressing portion disposed frontward of the pressure generating tube and including an projecting wall portion that is in a plate-like shape and extends in a vehicle front-rear direction; and a tube retaining member disposed opposite to the projecting wall portion and retaining the pressure generating tube between the projecting wall portion and the tube retaining portion.