In a fuel cell separator and the like, a technology for reducing the separation of a flow path rib which rectifies the flow of a fluid is desired.A separator used in a fuel cell is provided, the separator including: a separator main body that includes a fluid flow region through which a reactive gas or a coolant flows, a through-hole through which the reactive gas or the coolant flows, and a connection portion which connects the fluid flow region and the through-hole; and a flow rectifying portion that is arranged by being adhered on the connection portion and that rectifies flow of the reactive gas or the coolant between the fluid flow region and the through-hole, where the flow rectifying portion includes a plurality of protruded portions and a coupling portion which is thinner than the protruded portions and which couples the protruded portions.