To provide a diffusion measuring cell of transdermal absorption preparation capable of easily removing air bubble from the surface of skin and measuring the diffusibility (transdermal absorbance) of transdermal absorption preparation easily in a short time, and to provide a diffusion measuring device and diffusion measuring method using it.

The diffusion measuring cell of transdermal absorption preparation comprises a cell body that has an opening for installing the skin and the transdermal absorption preparation in an intermediate part of a side wall and has a receptor chamber for being filled with receptor liquid, and a lid body for fixing the skin and transdermal absorption preparation to the opening. The cell body is provided with a receptor liquid discharge passage communicating with the outside of the cell body from the upper part of the receptor chamber and a receptor liquid injection passage communicating with the outside of the cell body from the proximity of the lower end of the side wall of the receptor chamber.