The scintillation efficiency (quenching factor) of fluorine and calcium nuclei recoiling in a CaF 2 (Eu) crystal was measured in an energy region relevant to Dark Matter searches. The recoiling nuclei were obtained via the 1 9 F(n,n') and 4 0 Ca(n,n') reactions, where the neutron beam was provided via the d(d,n) 3 He reaction. The quenching factor of F and Ca nuclei in the CaF 2 (Eu) crystal was found to be 11-20%, and 9-23% relative to the electron equivalent energy for 53-192keV and 25-91keV recoil energies, respectively, and the energy dependence was observed. The quenching factor we measured here is a little larger than that of previous studies, which may depend on the Eu doping concentration of the crystal.