METHOD FOR PRODUCING BUTENE POLYMER

Provided is a method for producing a butene polymer, said method including a polymerization step, in which a polymerization reaction is carried out by bringing a starting material component that includes 20 mass% or more of isobutene into contact with a Lewis acid catalyst, and a distillation step, in which a butene polymer is obtained by performing distillation processing on a liquid to be processed that contains a reaction product of the polymerization reaction and a butene oligomer added to the reaction product, wherein the amount of the butene oligomer added is 25 parts by mass or more relative to 100 parts by mass of the reaction product. 本发明为种丁烯聚合物的制造方法，其包括如下工序：聚合工序，使包含20质量％以上异丁烯的原料成分与路易斯酸催化剂接触来进行聚合反应；及蒸馏工序，对含有聚合反应的反应产物和在反应产物中添加的丁烯低聚物的被处理液进行蒸馏处理而得到丁烯聚合物，丁烯低聚物的添加量相对于反应产物100质量份为25质量份以上。