The melting temperatures of $UO_2,;UO_2-6wt\%Gd_{2}O_3,;UO_2-12wt\%Gd_{2}O_3,;UO_2-2wt\%Er_{2}O_3,;and;UO_2-4wt\%Er_{2}O_3$ fuels were measured. Fuel materials were loaded in a tungsten capsule of which shape met the black body condition. The melting temperature was measured by the thermal arrest method during heating of the capsule in an induction furnace. The measured melting temperature of $UO_2$ fuel was $2815{pm}20^{circ}C$. The solidus and liquidus temperatures of $UO_2-Gd_{2}O_3;and;UO_2-Er_{2}O_3$ had also been measured, and it was observed that the solidus temperatures of them were lower than the liquidus temperature by $15{sim}25^{circ}C$. Measured melting temperatures of $UO_2,;UO_2-Gd_{2}O_3;and;UO_2-Er_{2}O_3$ fuels were as follows: