With the aim of measuring the circular dichroism (CD) spectra of biomaterials in aqueous solutions in the vacuum ultraviolet region of 310-140 nm, the optical and sample cell system endurable under high vacuum was first constructed to be incorporated into the synchrotron radiation beam line as the light source. The performance of the present system was con firmed to be satisfactory in the high vacuum off-line experiment by monitoring the CD spectra of ammonium d-camphor-10-sulfonate aqueous solutions.