To provide a method that efficiently separates R40 and CTFE, from a mixture including chloromethane (R40) and chlorotrifluoroethylene (CTFE).

A method of manufacturing CTFE includes a process in which an azeotrope-like composition consisting of 24-50% by mol of R40 and 76-50% by mol of CTFE, and an initial mixture including R40 and CTFE in which a content of CTFE in the total amount thereof exceeds 61% by mol are distilled to be separated into a first fraction in which a content of CTFE in the total amount of R40 and CTFE is lower than that of the initial mixture, and a second fraction in which a content of CTFE in the total amount of R40 and CTFE is higher than that of the initial mixture, whereby CTFE in which a concentration of R40 is lowered is obtained from the second fraction.