Autofluorescence of refrigerated raw scallop adductor muscle was investigated. Fluorescence of reduced nicotinamide adenine dinucleotide (NADH) with peak wavelength at 458 nm was observed in fresh scallops. The fluorescence emission intensity of NADH decreased until 48 hours in the storage time at time. As for the fluorescence excitation spectra, the peak wavelength became long from 361 to 369 nm as the storage time became long.