The present invention is to provide a nanosized phosphor exhibiting enhanced luminance as a molecular labeling phosphor by controlling an electrostatic charge of an inorganic phosphor. The nanosized phosphor is featured in that at least 90% of total particles have a particle size of 1 to 100 nm and an electrostatic charge of the total particles is in the range of −20 μC/g to 5 μC/g.