Output window unit

An output window unit provided in an electron beam irradiation device including an electron source and a housing accommodating the electron source, and configured to output an electron beam from the electron source to an outside of the housing, comprising:

• a window foil configured to transmit the electron beam toward the outside of the housing;
• and
• a support member fixed to the housing and configured to support the window foil,
• wherein the support member includes a mesh portion facing the window foil and in which a plurality of through-holes through which the electron beam from the electron source passes toward a window foil side are formed, a frame portion having a solid shape and formed integrally with the mesh portion to surround the mesh portion when viewed in a first direction that is a direction in which the window foil and the mesh portion face each other, an outer portion located outside the mesh portion and the frame portion when viewed in the first direction, and formed integrally with the mesh portion and the frame portion, and a recess formed to be recessed along the first direction,
• the outer portion includes a fixing portion used to fix the support member to the housing, and forms an edge portion of the recess, and
• the mesh portion and the frame portion form a bottom surface portion of the recess, so that a thickness of the mesh portion and the frame portion in the first direction is thinner than a thickness of at least a portion forming the edge portion in the outer portion.