1. A radio propagation estimating method of estimating a radio propagation path from a transmitting point of a radio wave to a receiving point of the radio wave, comprising: an acceptance step that accepts a position of the transmitting point and a position of the receiving point; an object surface acquisition step that acquires data on object surfaces that may affect the radio wave from the transmitting point; a receiving area setting step that sets a predetermined-size receiving area that includes the receiving point; a ray launching method-based path estimation step that estimates radio propagation paths of a plurality of rays via a ray launching method by using the acquired object surfaces, wherein the radio propagation paths are estimated for reaching the receiving point by reflecting the rays via one or more of the acquired object surfaces and the radio propagation paths of the plurality of rays are generated at the transmitting point; an object surface extraction step that extracts an only object surface from the acquired object surfaces, wherein the only object surface reflects the rays in the radio propagation paths of the rays reaching the receiving area estimated via the ray-launching method; and an imaging method-based path estimation step that estimates the radio propagation paths from the transmitting point to the receiving point via an imaging method using only non-overlapping object surfaces of the extracted object surfaces as being object surfaces on which the radio wave is reflected to change a direction of the radio propagation path.