The present invention provides a microchip which is made by bonding a first substrate having a groove provided at the substrate surface and a second substrate together, and has a fluid circuit therein, the fluid circuit having a separation portion for separating a first component, and a groove which constitutes the separation portion including an approximately V-shaped region surrounded by prescribed flow channel walls. At a top of the separation portion, a flow rate limiting portion limiting a flow rate of a fluid is preferably provided.