A front-illuminated-type
photodiode array comprises (a) a first-electroconductive-type
semiconductor substrate, (b) a first-electroconductive-type
electrode placed at the rear-face side of the semi-conductor substrate, (c) a first-electroconductive-type
absorption layer formed at the front-face side of the
semiconductor substrate, (d) a plurality of second-electroconductive-type regions formed from the surface of the
absorption layer to a certain distance into the
absorption layer such that the regions are arranged one- or two-dimensionally, (e) a second-electroconductive-type
electrode provided at part of each of the second-electroconductive-type regions, (f) an antireflective
coating that covers the top surface other than the individual second-electroconductive-type electrodes and that is for preventing reflection of an incoming lightwave, and (g) at least one leakage-lightwave-absorbing layer that is provided between the first-electroconductive-type
electrode and the absorption layer and that has an
absorption edge wavelength, λga, equal to or longer than the
absorption edge wavelength, λgr, of the absorption layer (λga≧λgr).