PROBLEM TO BE SOLVED: To provide a resin particle for fluorescent labeling in which a fluorescence dye is resistant to color degradation even when excitation light is applied for a long time at the time of immunostaining, and a fluorescent labeling agent for immunostaining comprising the same.SOLUTION: A resin particle for fluorescent labeling comprises an organic resin, a fluorescence dye and an antioxidant. A resin particle composed of the organic resin contains the fluorescence dye and the antioxidant.