A purification method of a solvent, which is a method of purifying a polymerization solvent used and recovered from a preparation of a polyolefin resin, wherein the polymerization solvent comprises impurities containing polyolefin wax, residual monomers having a lower boiling point than that of the polymerization solvent and oligomerization products of olefins, and the purification method comprises the steps of: separating the polymerization solvent from a reboiler by primary gas-liquid separation into a first vapor discharged to an upper part of the reboiler and a first solution containing polyolefin wax discharged to a lower part; separating the first vapor from a distillation column by secondary gas-liquid separation into a second vapor discharged to an upper part of the distillation column, a purified polymerization solvent discharged to a lower side, and a second solution containing polyolefin wax discharged to a lower part and resupplied to the reboiler; condensing the second vapor in a condenser to separate it into a third vapor containing residual monomers discharged to an upper part of the condenser and a third solution discharged to a lower part and resupplied to the distillation column; and discharging the first solution and the third vapor. which is a method of purifying a polymerization solvent used and recovered from a preparation of a polyolefin resin, wherein the polymerization solvent comprises impurities containing polyolefin wax, residual monomers having a lower boiling point than that of the polymerization solvent and oligomerization products of olefins, and the purification method comprises the steps of: separating the polymerization solvent from a reboiler by primary gas-liquid separation into a first vapor discharged to an upper part of the reboiler and a first solution containing polyolefin wax discharged to a lower part; separating the first vapor from a distillation column by secondary gas-liquid separation into a second vapor discharged to an upper part of the distillation column, a purified polymerization solvent discharged to a lower side, and a second solution containing polyolefin wax discharged to a lower part and resupplied to the reboiler; condensing the second vapor in a condenser to separate it into a third vapor containing residual monomers discharged to an upper part of the condenser and a third solution discharged to a lower part and resupplied to the distillation column; and discharging the first solution and the third vapor. separating the polymerization solvent from a reboiler by primary gas-liquid separation into a first vapor discharged to an upper part of the reboiler and a first solution containing polyolefin wax discharged to a lower part; separating the first vapor from a distillation column by secondary gas-liquid separation into a second vapor discharged to an upper part of the distillation column, a purified polymerization solvent discharged to a lower side, and a second solution containing polyolefin wax discharged to a lower part and resupplied to the reboiler; condensing the second vapor in a condenser to separate it into a third vapor containing residual monomers discharged to an upper part of the condenser and a third solution discharged to a lower part and resupplied to the distillation column; and discharging the first solution and the third vapor.