The new SR-9M has been developed specifically for chronic experiments on mice by remodeling the SR-6M; a compact yet stable stereotaxic instrument. Fixation by the chamber frame has permitted repeated fixations in the same position in an unanesthetized state, thereby enabling not only acute experiments but also chronic experiments without causing damage to the animal. Without the need for anesthetization, the SR-9M can be used for visual and/or auditory experiments. The head holding device (SR-9AM) can be removed from the base plate so it can be placed under a microscope. For the AP frame bar, to which manipulators are fixed, a long 18.7mm square bar is provided on both the left and the right-hand side, enabling attachment of the SM-15 and many other kinds of accessories.