An optical module includes optical transmission member, optical element, substrate, electrode pad between the optical element and external circuit, and optical block including optical transmission member mounting portion. The optical transmission member mounting portion is formed on the optical block in optical axis direction such that optical transmission efficiency is the maximum. A manufacturing method of the optical module includes mounting and electrically connecting the optical element on one face of the substrate, calculating a position on a 2-dimensional plane of optical input/output point of the optical element, forming base material of the optical block to impregnate the optical element onto the substrate, forming the optical transmission member mounting portion at the position on the 3-dimensional plane of the optical input/output point calculated in the former step on the base material, and mounting the optical transmission member on the optical transmission member mounting portion.