An optical module includes: a substrate including a through hole, a first chip including a first heating member and disposed in the through hole, a second chip including a second heating member and bonded to a first upper surface of the substrate and a second upper surface of the first chip via bumps, and a first heat sink adhered to a lower surface of the substrate with a first adhesive and adhered to a lower surface of the first chip with a second adhesive, wherein the substrate includes a slit which is provided on a side of a first portion, to which the second chip is bonded, of the substrate with respect to the through hole, and communicates with the through hole.