A trichlorosilane refining method, comprising: introducing a feed containing a trichlorosilane through an inlet port of a divided wall distillation column, which has an upper column region, a preliminary separation region, a main separation region and a lower column region formed therein and comprises the inlet port installed to introduce a feed containing a trichlorosilane into the preliminary separation region, a first outlet port through which a low boiling point component present at the upper column region flows out, a second outlet port through which a refined trichlorosilane component present at the main separation region flows out and a third outlet port through which a high boiling point component present at the lower column region flows out; introducing the refined trichlorosilane component which flows out through the second outlet port formed at the 6/9 to 8/9 section of the divided wall section of the main separation region, into a first distillation column coupled to the divided wall distillation column to introduce the component flowing out through the second outlet port; wherein the term "6/9 to 8/9 section of the divided wall section" refers to a section spanning from a point spaced apart from the uppermost portion of the main separation region by 6/9 times the length of the main separation region to a point spaced apart from the uppermost portion of the main separation region by 8/9 times the length of the main separation region when the length of the main separation region is divided into 9 equal parts, wherein the upper or lower column region has an open length of 800 mm to 3,500 mm, and wherein the divided wall of the divided wall distillation column has a length of 30% or more with respect to a total theoretical plate number of the divided wall distillation column, wherein the first outlet port or the component flowing out through the first outlet port is maintained at a temperature of 82.2°C to 92.2°C under an upper column pressure of 670 kPa (5.8 Kg/sqcmG), wherein the second outlet port or the component flowing out through the second outlet port is maintained at a temperature of 96.4 °C to 106.4 °C under an upper column pressure of 670 kPa (5.8 Kg/sqcmG), and wherein the third outlet port or the component flowing out through the third outlet port is maintained at a temperature of 139.9 °C to 149.9 °C under an upper column pressure of 670 kPa (5.8 Kg/sqcmG). introducing a feed containing a trichlorosilane through an inlet port of a divided wall distillation column, which has an upper column region, a preliminary separation region, a main separation region and a lower column region formed therein and comprises the inlet port installed to introduce a feed containing a trichlorosilane into the preliminary separation region, a first outlet port through which a low boiling point component present at the upper column region flows out, a second outlet port through which a refined trichlorosilane component present at the main separation region flows out and a third outlet port through which a high boiling point component present at the lower column region flows out; introducing the refined trichlorosilane component which flows out through the second outlet port formed at the 6/9 to 8/9 section of the divided wall section of the main separation region, into a first distillation column coupled to the divided wall distillation column to introduce the component flowing out through the second outlet port; wherein the term "6/9 to 8/9 section of the divided wall section" refers to a section spanning from a point spaced apart from the uppermost portion of the main separation region by 6/9 times the length of the main separation region to a point spaced apart from the uppermost portion of the main separation region by 8/9 times the length of the main separation region when the length of the main separation region is divided into 9 equal parts, wherein the upper or lower column region has an open length of 800 mm to 3,500 mm, and wherein the divided wall of the divided wall distillation column has a length of 30% or more with respect to a total theoretical plate number of the divided wall distillation column, wherein the first outlet port or the component flowing out through the first outlet port is maintained at a temperature of 82.2°C to 92.2°C under an upper column pressure of 670 kPa (5.8 Kg/sqcmG), wherein the second outlet port or the component flowing out through the second outlet port is maintained at a temperature of 96.4 °C to 106.4 °C under an upper column pressure of 670 kPa (5.8 Kg/sqcmG), and wherein the third outlet port or the component flowing out through the third outlet port is maintained at a temperature of 139.9 °C to 149.9 °C under an upper column pressure of 670 kPa (5.8 Kg/sqcmG).