According to the present invention, a continuous layer liquid used as a continuous layer of a diffusion phenomenon is injected into the first reservoir, and passed through the channels to the second reservoirs to fill the plurality of radially formed channels with the continuous layer liquid. Then, a predetermined amount of diffusion experiment reagent, for example, a coloring liquid used as a diffusion substance of the diffusion phenomenon is injected into the first reservoir. This causes the diffusion experiment reagent to be diffused from the first reservoir to the second reservoirs only by the diffusion phenomenon. At this time, the radially formed channels have the different sectional areas, and thus the diffusion experiment reagent is diffused through the channels at different velocities. This allows the diffusion phenomena that occur in the micro channels or the diffusion velocities to be observed or measured with ease using an inexpensive device.