Provided is a slide device which includes a fixed-side slide member having an annular-shaped first slide surface, and a rotary-side slide member having an annular-shaped second slide surface, with the slide device being configured such that the first slide surface and the second slide surface are positioned opposite to each other, and an outer peripheral side of the fixed-side slide member and an outer peripheral side of the rotary-side slide member are brought into contact with a liquid containing a blood component, and a region where the first slide surface and the second slide surface face each other along the rotary-side slide member, the first slide surface and the second slide surface are brought into contact with each other on an outermost periphery of the opposite-facing region of the first and second slide surfaces.