In an optical circuit using a Mach-Zehnder-type element, it is difficult to obtain an optical circuit which has a less wavelength dependence and is suitable for achieving high integration. Accordingly, an optical circuit according to the present invention includes: a first Mach-Zehnder-type element including a first branch waveguide, a first branching/combining unit connected to one end of the first branch waveguide, and a second branching/combining unit connected to another end of the first branch waveguide and having a branch configuration different from that of the first branching/combining unit; and a second Mach-Zehnder-type element including a second branch waveguide, a third branching/combining unit connected to one end of the second branch waveguide, and a fourth branching/combining unit connected to another end of the second branch waveguide and having a branch configuration different from that of the third branching/combining unit. The first branch waveguide and the second branch waveguide each include a phase difference adjustment means. In the second branching/combining unit and the third branching/combining unit, light coupling between two basic modes with a phase inverted and a higher-order mode, is smaller than that in the first branching/combining unit and the fourth branching/combining unit. The first Mach-Zehnder-type element and the second Mach-Zehnder-type element are connected with each other through the second branching/combining unit and the third branching/combining unit.