Measurement object holder, biological holder and the optical measuring device

The invention enables smooth measurement when obtaining optical tomographic information that takes a living body as a measurement object. A specimen holder (64) used as a measurement object holder is formed by a material having optical properties in which near-infrared light and fluorescence propagate while scattering isotropically. Further, the specimen holder (64) is divisible into a block 66 and a block 68 in a plane including the axial center. Recessed portions 66A and 68A are formed in the blocks (66, 68) in conformity with the outer shape and size of a specimen. A specimen 18 is accommodated in a cavity portion formed by the recessed portions (66A, 68A) such that its epidermis is in close contact with. Thereby, the specimen holder (64) holds the specimen (18) in a state where the original shape of the specimen (18) and the organ positions in the specimen (18) are maintained while performing a measurement with respect to the specimen (18).