An optical module comprises: a sub-mount 1, having four photodiodes 12 and two guide grooves 10 disposed on an optical element mounting surface 16; a fiber fixing member 2, having four V-grooves 21, four concave mirrors 22, and two guide rails 20 disposed on an optical fiber fixing surface 26; and four optical fibers 3, fixed to the fiber fixing member 2. With this optical module, the sub-mount 1 and fiber fixing member 2 are aligned and fixed by the fitting together of the guide grooves 10 and guide rails 20. A passive alignment type optical module that enables mass production and cost reduction is thus realized.