To provide an objective lens system for vertical fluorescence which allows the good transmission of exciting light, lessens the occurrence of self- fluorescence and is well corrected of various aberrations.

This objective lens system has, successively from a sample side, a front lens group GF and a rear lens group GR. The lens component arranged on at least the sample side among the lens components constituting the front lens group GF is formed of a prescribed optical material which has the substantially higher transmittance to the exciting light and substantially lessens the occurrence of the fluorescence to the exciting light as compared with the other lens components constituting the objective lens system for vertical fluorescence. The exciting light supplied in the optical path between the front lens group GF and the rear lens group GR is introduced via the front lens group GF to the sample and the image of the sample is formed in accordance with the fluorescence from the sample via the front lens group GF and the rear lens group GR.