A valve disposed at a flow path, the valve comprising: a substrate having a first surface in which a hole having an opening section is formed; and a diaphragm member that comprises: an outer edge section fixed to at least part of an inside of the hole; and a central portion having a thin film shape and having a thickness which is smaller than a thickness of the outer edge section, wherein a first surface (t) of the diaphragm member facing the first surface of the substrate is a plane substantially parallel to the first surface of the substrate, and at least a central portion of a second surface of the diaphragm member (u) opposite to the first surface of the diaphragm member has a recessed concave shape, and wherein a flow of a fluid in the flow path is controlled by deforming the diaphragm member, and the first surface of the substrate is a fluid contact surface, and the diaphragm member controls the flow of the fluid in the flow path by deforming in a direction perpendicular to an axis of the flow path, characterized in that an expansion section in which an end portion of the inner wall surface that constitutes the opening section is expanded outward in the radial direction of the hole is formed, a longitudinal hole section in which at least part of the expansion section except for a peripheral edge portion of the hole enters further inside the substrate than the peripheral edge portion is formed, the outer edge section of the diaphragm member is formed to extend in the longitudinal hole section, and the inner wall surface that constitutes the longitudinal hole section and the outer edge section of the diaphragm member are at least partially adhered to each other. a diaphragm member that comprises: an outer edge section fixed to at least part of an inside of the hole; and a central portion having a thin film shape and having a thickness which is smaller than a thickness of the outer edge section, an outer edge section fixed to at least part of an inside of the hole; and a central portion having a thin film shape and having a thickness which is smaller than a thickness of the outer edge section, wherein a first surface (t) of the diaphragm member facing the first surface of the substrate is a plane substantially parallel to the first surface of the substrate, and at least a central portion of a second surface of the diaphragm member (u) opposite to the first surface of the diaphragm member has a recessed concave shape, and wherein a flow of a fluid in the flow path is controlled by deforming the diaphragm member, and the first surface of the substrate is a fluid contact surface, and the diaphragm member controls the flow of the fluid in the flow path by deforming in a direction perpendicular to an axis of the flow path, characterized in that an expansion section in which an end portion of the inner wall surface that constitutes the opening section is expanded outward in the radial direction of the hole is formed, a longitudinal hole section in which at least part of the expansion section except for a peripheral edge portion of the hole enters further inside the substrate than the peripheral edge portion is formed, the outer edge section of the diaphragm member is formed to extend in the longitudinal hole section, and the inner wall surface that constitutes the longitudinal hole section and the outer edge section of the diaphragm member are at least partially adhered to each other.