An optical module includes a transmitting member. The transmitting member is fixed to a cap member so as to cover a through-hole. On the assumption that the height of one point on a first surface in a state in which the transmitting member is detached from the cap member is zero and the direction toward the outside of the optical module is a positive direction, the amount of warp that is a difference between the displacement at the central point and the displacement at a standard point, on the first surface, corresponding to a reference point, on the projection image, away from a center of gravity by a particular distance is different between a first geodesic line and a second geodesic line, the displacement being a height of the one point in a direction of the optical axis in a state in which the transmitting member is fixed to the cap member. The transmitting member is joined to the cap member at the first surface or the second surface.