A separator for fuel cell, comprising: a corrugated portion formed to have a corrugated cross section where a first groove that is concave to a first surface to form a flow path for a first fluid on the first surface and a second groove that is concave to a second surface opposite to the first surface to form a flow path for a second fluid on the second surface are arranged alternately and repeatedly in a first direction perpendicular to a second direction in which planar shapes of each of the first groove and the second groove are extended, wherein each of the second grooves has a plurality of shallower groove sections formed to have a less depth from the second surface than depth of a remaining groove section and provided to form a communication flow channel on the first surface side, which is arranged to communicate between two flow path spaces for the first fluid that are adjacent to each other across the shallower groove sections, and each of the shallower groove sections included in each of the second grooves is formed at a position aligned with a shallower groove section included in another adjacent second groove, characterized in that the first surface of the corrugated portion has a wall member that is formed on a first side of a deeper groove section that is a part of the second groove other than the shallower groove section in the first direction to be located on an extension of a boundary wall between the deeper groove section and the shallower groove section, and a floor member that is formed on the first side of the shallower groove section to be located on an extension of a floor surface of the shallower groove section. a corrugated portion formed to have a corrugated cross section where a first groove that is concave to a first surface to form a flow path for a first fluid on the first surface and a second groove that is concave to a second surface opposite to the first surface to form a flow path for a second fluid on the second surface are arranged alternately and repeatedly in a first direction perpendicular to a second direction in which planar shapes of each of the first groove and the second groove are extended, wherein each of the second grooves has a plurality of shallower groove sections formed to have a less depth from the second surface than depth of a remaining groove section and provided to form a communication flow channel on the first surface side, which is arranged to communicate between two flow path spaces for the first fluid that are adjacent to each other across the shallower groove sections, and each of the shallower groove sections included in each of the second grooves is formed at a position aligned with a shallower groove section included in another adjacent second groove, characterized in that the first surface of the corrugated portion has a wall member that is formed on a first side of a deeper groove section that is a part of the second groove other than the shallower groove section in the first direction to be located on an extension of a boundary wall between the deeper groove section and the shallower groove section, and a floor member that is formed on the first side of the shallower groove section to be located on an extension of a floor surface of the shallower groove section.