A light detection device includes a Fabry-Perot interference filter, a light detector, a spacer that has a placement surface on which a portion outside a light transmission region in a bottom surface of the interference filter is placed, and an adhesive member that adheres the interference filter and the spacer to each other. Elastic modulus of the adhesive member is smaller than elastic modulus of the spacer. At least a part of a lateral surface of the interference filter is located on the placement surface such that a part of the placement surface of the spacer is disposed outside the lateral surface. The adhesive member is disposed in a corner portion formed by the lateral surface of the interference filter and the part of the placement surface of the spacer and contacts each of the lateral surface and the part of the placement surface.