The neutron reflectivity of a 6 LiTi multilayer mirror with a Ni reflector at the base has been measured using a time-of-flight spectrometer and a reflectometer. The results show that the reflectivities rise to 0.5 at 560 Å, which corresponds to the Ni critical wavelength, decrease to 0.2 with increasing neutron wavelength, and then rise towards unity at about 800 Å. This implies that neutrons in wavelength region between 560 Å and 800 Å penetrate through the 6 LiTi multilayer and are absorbed by 6 Li. The application of the 6 LiTi multilayer to a neutron converter for an ultracold neutron detector is discussed.