A mixing device includes a mixing section that mixes a liquid-phase fluid with one kind or two or more kinds among a solid, a gas, and a liquid-phase fluid different from the above-mentioned liquid-phase fluid, in which the mixing section includes a supply hole for a fluid, a discharge hole for the fluid, a flow path that makes the supply hole and the discharge hole communicate with each other, and a plurality of pins that protrudes from the flow path, and a fluid that includes materials to be mixed is supplied from the supply hole to the flow path, mixed by passing through the flow path with the contact with the pins, and discharged from the discharge hole.
