Fluorescent labeling reagent

A fluorescent labeling reagent comprising:

• an inorganic fluorescent particle capable of emitting light with a wavelength of 650 nm to 1600 nm when excited by light with a wavelength of 650 nm or longer;
• and
• a material (A) capable of absorbing or binding to a material (B) of biological origin, the material (A) being integrated with the inorganic fluorescent particle,
• wherein the material (A) is a functional bead matrix composed of an inorganic material or a polymer material of which surface is chemically modified to have a molecule capable of absorbing or binding to a specific biomolecule,
• wherein the inorganic fluorescent particle is dispersed into the functional bead matrix, whereby the material (A) is integrated with the inorganic fluorescent particle,
• wherein the inorganic fluorescent particle comprises one or more rare earth element capable of producing fluorescence as dopants selected from the group consisting of cerium, praseodymium, neodymium, gadolinium, holmium, erbium, thulium, ytterbium, europium, terbium, samarium, and dysprosium, and
• wherein the inorganic fluorescent particle has a garnet structure of yttrium, aluminum and oxygen, and the inorganic fluorescent particle is a crystalline particle in which the one or more rare earth element is incorporated into the garnet structure.