Provided is a photocatalyst layer that improves the photocatalytic performance while suppressing detachment of photocatalyst particles. The photocatalyst layer has a front surface and a rear surface on the opposite side of the front surface. The photocatalyst layer includes photocatalyst particles and a binder. The photocatalyst layer has a first region containing the photocatalyst particles and a second region containing the binder and not containing the photocatalyst particles. The photocatalyst particles include tungsten oxide particles. The photocatalyst particles have contact points being in contact with the rear surface. The ratio of the thickness of the second region to the number-average secondary particle diameter of the photocatalyst particles is 0.20 or more and 0.80 or less.