PURPOSE: To rapidly adjust the optical axis of a parallel transmission optical module with high accuracy without being affected by the parallel number of optical fibers and without depending on the input characteristics of optical elements.

CONSTITUTION: An optical element array chip 23 has optical elements 41 arranged at prescribed intervals on its front surface. A substrate consisting a V-grooved substrate 1 and a retaining substrate 2 aligns and holds the fiber end faces of the plural optical fibers 26 opposite to the corresponding optical elements 4 to respectively hold the optical coupling between the corresponding optical fibers 26 and the optical elements 4. The optical element array chip 23 is provided with electrode pads 5a and 5b on both further outer sides of the optical elements 4 existing on the outermost side. Conductor pins 3a and 3b are respectively arranged in the positions facing the electrode pads 5a and 5b on the substrate. These conductor pins 3a, 3b and the optical fibers 26 are aligned and held on the basis of the V-grooves 11, 12a, 12b.