It is to provide an optical element, an optical module, an optical connector, and an optical module manufacturing method that can quickly and very accurately control the amount of outgoing light to a desired amount when incident light is outputted, reduce costs, and enhance manufacturing efficiency.A diffraction grating 9 having a periodic structure made from a plurality of grating grooves 10 and formed to allow control of an amount of outgoing light using polarization-dependent characteristics when incident light is outputted as the outgoing light and a mark 11 indicating at least one of either a grating groove 10 direction of the diffraction grating 9 or a periodic direction of the diffraction grating 9 are included.