Using Einstein-Cartan-Dirac theory, we study the effect of torsion on neutr
ino oscillation. We see that torsion cannot induce neutrino oscillation, bu
t affects it whenever oscillation exists for other reasons. We show that th
e torsion effect on neutrino oscillation is as important as the neutrino ma
ss effect, whenever the ratio of neutrino number density to neutrino energy
is similar to 10(69) cm(-3)/eV, or the number density of the matter is sim
ilar to 10(69) cm(-3).