PROBLEM TO BE SOLVED: To provide a diffuser capable of previously preventing liquid drips in a diffusing section.SOLUTION: A pricking portion 81 of a suction wick 17 is put into a bottom surface 32 of a cap 14 attached to a container 11 to open an insertion hole 41 and the suction wick 17 is inserted thereinto. In the inside of the container 11, the volume partial internal pressure of the inserted suction wick 17 is increased. In this case, an undercut 93 is formed in the peripheral surface 42 of the suction wick 17, and a gap 92 is formed by the undercut 93 between the inner edge 91 of the insertion hole 41 and the suction wick 17. With this configuration, an increased pressure in the container 11 is released outside through the gap 92 formed by the undercut 93, and thus an increase in an inner pressure can be prevented.
