Structural body

A structural body comprising:

• a porous partition portion which forms at least one cell to be used as a flow path of a fluid;
• a function layer which is provided on an inside surface of the partition portion, which contains a metal ion, and which is transformed by light;
• and
• a protective layer which is provided at an end portion of the inside surface of the partition portion and which is not transformed by light,
• wherein the protective layer is directly provided on the inside surface of the partition portion,
• wherein the protective layer has a slope so that the thickness thereof increases from one end at a function layer side to an end at an end surface side of the structural body, and in a region of 0.1 mm from the end at the function layer side, an angle θ of the slope to the inside surface of the partition portion is 45° or less,
• wherein the function layer is disposed on a surface of the protective layer at an interface between the function layer and the protective layer in the region of the slope of the protective layer, and
• wherein when the maximum length of an opening of the cell is represented by A (mm), and the length of the protective layer from an end surface of the structural body is represented by B (mm), the relationship of B/A≥0.4 is satisfied.