To provide a simple and efficient mixing apparatus related to a piping apparatus.

This mixing apparatus 10 is provided with a doughnut-shaped disk 11 having a through-hole 11a in the central part and a cylindrical perforated pipe 12 which has many pores on the cylindrically circumferential surface, the inlet end face of which is opened and connected to the through-hole 11a and which has a collision plate 13 arranged on the outlet end face. The apparatus 10 is fit fixedly to a pipe 1 so that the outer periphery of the disk 11 is made in contact with the inner wall surface of the pipe 1 all around the periphery.