Density and temperature modulations were induced in JT-60U plasmas using sinusoidal modulation of gas puff injection. From an analysis of the density modulation, the particle diffusion coefficients were evaluated to be 0.2 m2/s in the central region and 0.8 m2/s in the edge region of ohmically heated plasmas. Furthermore, from an analysis of the electron temperature modulation, the ratio of the heat and particle diffusion coefficients, χe/D, was estimated to be between 5 and 10