We present high performance of the PIN-type ZnSe-based photodetector with optimized device structure grown by MBE. The external quantum efficiency of present photodetector is found to be improved over 62% at 458 nm under zero-bias condition without anti-reflection coating process. In addition, this well-designed PIN photodetector can be further improved up to 85% in blue optical region using anti-reflection coating of a thin SiO2 films.