The authors investigated the effect of p-type AlGaN electron blocking layer (EBL) on the optical and the electrical properties of GaN-based blue light-emitting diodes. 405- and 325-nm photoluminescence (PL) analyses showed the maximum intensities from 18% and 12% p-AlGaN EBL, respectively. Both PL methods would make a clear distinction between the optical qualities of InGaN well and the carrier transport from n-/p-type layers to active layer. From electroluminescence (EL) measurement, it found that the highest EL intensity was obtained at 12% p-AlGaN EBL, which was consistent with the result of 325-nm PL. From these results, the authors concluded that the 12% p-AlGaN EBL would effectively suppress the carrier overflow and that the problem for carrier transport was dominant at a higher than 18% Al in p-AlGaN EBL by measuring 325-nm PL and the photogenerated current.