EPR and optical absorption spectra of Mn° centers in NaCl are studied. Three kinds of optical absorption spectra A , B and C which are ascribed to atomic manganese centers are found: each of these spectra consists of the allowed transitions from the ground state 3 d 5 4 s 2 to the excited states 3 d 5 4 s 4 p and 3 d 5 4 s 5 p . Each spectrum has a structure: the splitting for the spectrum A is much smaller than those for the spectra B and C . The spectrum A which is formed by the X-irradiation at liquid helium temperature changes above 20°K into spectrum B . It is suggested that the spectrum A and the spectrum B arise from Mn° at a lattice site (Mn°- A center) and in an off-centered position (Mn°- B center), respectively. It is shown that the spectrum C is associated with the Mn° center which produces EPR spectrum with A =15.5×10 -4 cm -1 . It is suggested that the spectrum C is associated with Mn° at the interstitial site (Mn°- C center).