To provide a fluorometric probe capable of receiving stably fluorescence generated from a sample irradiated with an exciting light at the luminous energy which maximizes photoreception luminous energy.

This fluorometric probe has an optical fiber with the optical path of the fluorescence being identical to the optical path of the exciting light, and a lens arranged between an end part cross section of the optical fiber and the sample, an exciting light beam NA is set as sin is 0.14 or larger to 0.31 or smaller, a fiber core diameter is 200 m or larger, and a fiber NA is 0.22 or larger, where represents the irradiation angle of the exciting light in a convergence position of the exciting light, when the exciting light emitted from the optical fiber and irradiated is received via the lens and when fluorescence generated from the sample is condensed via the lens.