To provide a mixer apparatus capable of mixing fluids by a simple configuration without requiring additional devices.

A mixer element 3 includes a pair of jet orifices 7 and 7, and the first fluids S jetted from a pair of the jet orifices 7 and 7 are allowed to collide with each other at an angle of 180° or below in an outflow direction within a collision space 9 to be discharged from a fluid outlet 11. A suction hole 13 for sucking a second fluid K is provided behind the collision space 9 and the second fluid K is sucked from the suction hole 13 by the negative pressure generated behind the collision space 9 by the mutual collision of the first fluids S jetted from a pair of the jet orifices 7 and 7, and the first and second fluids S and K are allowed to collide with each other in the collision space 9 to be mixed.