The Wilhelmy plate technique was used to measure the dynamic surface tension of poly(N-isopropylacrylamide)(poly(NIPAM)) at the air-water interface as a function of poly(NIPAM) concentration and temperature. Initial periods of a negligible decrease of the dynamic surface tension were observed at the lowest concentration of poly(NIPAM). The decay rate of the surface tension was well interpreted by taking account of the solution properties of poly(NIPAM) under the assumption of diffusion-controlled adsorption kinetics. The experimental data were numerically fitted with an empirical Hua-Rosen equation, and they were in good agreement with each other. Furthermore, the ellipsometric results were-compared with those for the poly(NIPAM) monolayer spread at the air-water interface from its aqueous solution.