An optical module includes: an optical sub-assembly; and a flexible substrate including an insulating film, an interconnection pattern, and a spacer layer, the flexible substrate being connected to the optical sub-assembly. The insulating film has some projections, the projections protruding from a basic area in a first direction, the projections being arranged in a second direction perpendicular to the first direction, the insulating film having a flat shape with a recess between an adjacent pair of the projections. The interconnection pattern includes some pads in the basic area on a first surface of the insulating film, the pads being arranged in the second direction. The pads include some first pads adjacent to the respective projections, the pads including at least one second pad adjacent to the recess. The spacer layer is on the first surface and at each of the protrusions.