Abstract: A microchannel has a substrate body; a separation channel which is formed within the substrate; at least two (first and second) connection ports which are formed at one end of the separation channel close to the thickness direction perpendicular to the longitudinal direction of the substrate body; and first and second branch channels connected respectively to the first and second connection ports. When the substrate body is perpendicular to gravity, a blood sample containing blood cells and plasma, flows from one end of the separation channel. Before the blood sample gets to the other end of the separation channel, the blood cells in the blood sample settle out. The blood cells having settled out are then separated into the branch channel.

Abstract: It is intended to provide a microchannel for separating blood plasma whereby blood plasma can be conveniently separated on a microchip. A microchannel comprising: a substrate body (10a); a separation channel (11) which is formed within the substrate body (10a) and extended in the direction parallel to the longitudinal direction of the substrate body (10a); at least two (first and second) connection ports (13a, 14a) which are formed at one end of the separation channel (11) close to the thickness direction perpendicular to the longitudinal direction of the substrate body (10a); and first and second branch channels (13, 14) which are formed within the substrate body (10a) and connected respectively to the first and second connection ports (13a, 14a). In the state where the substrate body (10a) is extended perpendicular to the direction of gravitational force, a blood sample containing blood cells and plasma is flown from one end (11a) side of the separation channel (11).