Ultraviolet-light emitting diodes (UV-LEDs) have garnered attention for their efficient bacterial inactivation. However, in previous studies, it has been difficult to strictly compare the bacterial inactivation effect of UV irradiation among wavelengths differing by a few nanometers because detailed UV irradiation conditions for comparison, such as the LED characteristics at each wavelength and power supply characteristics, have not been established. Therefore, this study aimed to evaluate UV inactivation of 10 bacterial strains across 13 wavelengths (250-365 nm) using a standardized irradiation system previously reported to identify the most effective wavelengths for prevention of bacterial infection and contamination. Bacterial inactivation dose response curves were generated to determine the fluence required to archive 1-3 log