Three-dimensional position detecting device and method for using the same

A three-dimensional position detecting device includes an electromagnetic radiation source, a first sensing module having first sensing elements, and a second sensing module having second sensing elements. The first and the second sensing elements receive different radiation energies from different spatial direction angles generated by the electromagnetic radiation source relative to the first and the second sensing elements, so values of two spatial direction angles of the electromagnetic radiation source relative to the first and the second sensing modules are obtained according to magnitude relationship of the radiation energies received by the first and the second sensing modules. According to matrix operation of two spatial distances from the electromagnetic radiation source to the first and the second sensing modules and the two spatial direction angles, a spatial coordinate position of the electromagnetic radiation source relative to the first and the second sensing modules is obtained.