In an optical modulator according to the invention, with respect to two MZ type optical modulators connected to each other in tandem by a curved folded waveguide on an identical substrate, a longitudinal direction of an MZ type optical waveguide unit on an optical input port side is obliquely arranged to a longitudinal direction of an MZ type optical waveguide unit on an optical output port side, and a curvature radius of the curved folded waveguide is made larger than a half of an interval between the optical input/output ports to decrease a length of a feeder portion of a signal electrode corresponding to the MZ type optical waveguide unit on the input side. Therefore, a loss of an electric signal propagated through the signal electrode can be reduced.