Recently, it is stressed that petroleum is used as a raw material rather than energy in view of efficient resource utilization. LCO, specifically, which includes lots of raw materials, is used only as a fuel. 2,6-dimethylnaphthalene (2,6-DMNA) in LCO is paid attention as raw materials for engineering plastic (PEN plastic), polymer liquid crystal etc. In the previous work, we were investigated the recovery of 2,6-DMNA from LCO by distillation-extraction combination. This work investigated the high-purity purification using an extract recovered from LCO by the previous work. Melt crystallization by using the extract (concentration of 2,6-DMNA: 10.43%) as a raw material and solute crystallization by using the crystal recovered by melt crystallization as a raw material was carried out. A solvent of solute crystallization used was a mixture of methanol and acetone. By melt-solute crystallization operation, 2,6-DMNA with high-purity such as 99.7% was recovered.