Light-transmitting resin member

A light-transmitting resin member, in at least a part of a surface of which a plurality of groove structures configured with a plurality of linear protrusion portions and a plurality of linear recess portions are formed, wherein

• the linear protrusion portions and the linear recess portions extend in directions parallel with each other, and
• the grooves are formed at a pitch at which transmittance of visible light incident at an incident angle in a predetermined range becomes approximately constant, the visible light being incident on a region, in which the grooves are formed, in the surface, the visible light being transmitted through the light-transmitting resin member, wherein
• the linear protrusion portions and the linear recess portions extend in directions parallel with each other,
• an average value W1 of widths of the linear protrusion portions satisfies 75 nm≤W1≤200 nm,
• an average value W2 of widths of the linear recess portions, the average value W2 being a width of the grooves, satisfies 75 nm≤W2≤450 nm,
• a pitch P between the grooves neighboring each other satisfies 150 nm≤P≤600 nm,
• an aspect ratio D/W2 of a depth D of the grooves to the width W2 of the grooves satisfies 2.0≤D/W2,
• an angle θ1 of a side wall of the grooves relative to a reference plane satisfies 60°≤θ1≤90°, and
• a contact angle θ2 of water relative to the surface in which the grooves are not formed satisfies 60°≤θ2≤90°.