PURPOSE: To provide a semiconductor photodetector element provided with a photodetecting part which can receive the incident light from the direction nearly parallel to a main plane of a semiconductor substrate and manufacture thereof, and a semiconductor photodetector element module having an improved reliability of wiring which can be assembled by a simplified operation.

CONSTITUTION: On the end part of an n+-InP substrate 1a, a surface 1c (inclined surface) which is inclined with respect to a main surface of that substrate is formed and a first conductivity type semiconductor epitaxial layer E2 is formed to cover the inclined surface 1c and the main surface 1a. Zn is diffused into the region of first conductivity type semiconductor epitaxial layer E2 which is formed over the inclined surface 1c and the region which is connected to the former region and is formed over the main surface 1a, resulting in formation of a p+-type impurity diffused region 7a. Furthermore, the p+-type impurity diffused region 7a of the region which is formed over the inclined surface 1c is made to serve as a photodetecting part, while on the surface, of semiconductor epitaxial layer E2, parallel to the main surface of n+-InP substrate 1a, a front electrode 6 for taking out electric signals generated by the photodetecting part is formed.