The pressure dependence of the spin reorientation in Er 2 Fe 1 7C 2 was measured by means of ac initial susceptibility under 1-12 kbar. As a result, the spin reorientation temperature shifted toward the higher side with increasing pressure. From this experimental observation it is believed that the pressure increases the anisotropy energy of the rare earth. That is, the pressure effect is equal to increasing the absolute value of the negative second-order crystalline field coefficient A 2 0 . The change in A 2 0 is estimated to be reasonable from the value of Young's modulus of Er 2 Fe 1 7 .