An enzymatic treatment method using alcalase was introduced to improve the moisture characteristic of the polyamide fiber. The alcalase treatment conditions such as the pH, treatment temperature, enzyme concentration, and treatment time were optimized by measuring the amino groups. The changes in the weight loss, tensile strength, moisture regain, water contact angle (WCA), and water absorption rate of the polyamide fiber with the changes in the alcalase treatment conditions were evaluated. The optimum alcalase treatment conditions for polyamide fiber were found to be a treatment temperature of 50℃, a treatment time of 50 minutes, an alcalase concentration of 10% (owf), and a pH of 7.0. The ethylenediaminetetraacetic acid (EDTA) and L-cysteine accelerated the activity of the enzyme; however, they did not have an effect on the amino group production of the fiber surface. The alcalase treatment of the polyamide fiber improved the fiber`s moisture regain, WCA, and absorption rate due to the amino group on the fiber surface. The results showed that the alcalase treatment of polyamide fiber is an effective method to improve the moisture characteristic of the polyamide fiber.