The methods to decrease crease of cotton/spandex knit fabric using heat treatment were investigated. Dry heat treatment, hot water treatment, and steam treatment were used to set spandex yarn in knit fabric. Length changes of spandex yarn in knit fabric. Length changes of spandex yarn in knit fabric treated or stored under various conditions were investigated. Wrinkle recovery rates, elongation, and tensile strength changes of the fabric were also measured. The length change of the spandex yarn in knit fabric treated with steam was larger than those treated with dry heat and hot water. It increased with increasing extension of spandex yarn in knit fabric. A long loop length of cotton yarn in knit fabric resulted in a smaller length change of the spandex yarn subjected to the same heat treatment due to the low extension of spandex yarn in fabric. The length of spandex yarn in knit fabric increased during storage even at room temperature. The crease of cotton/spandex knit fabric could be removed by setting spandex yarn in the fabric. Considering the strength retention and elongation, steam treatment was found to be the most effective to remove the crease of the knit fabric.