A curved waveguide is a curved waveguide that propagates laser light entering from the laser diode as propagating light. The curved waveguide includes a core that is curved in one direction where the propagating light can be propagated and that includes outer surfaces along a propagating direction of the propagating light defined by four surfaces including first and second planar surfaces that curve in respective planar surfaces and that are positioned to face each other, and inside and outside curved surfaces that connect the first and second planar surfaces: an outside metal cladding that is positioned in a direction orthogonal to an oscillation direction of an electric field of the propagating light in a cross section orthogonal to the propagating direction of the propagating light and along the outside curved surface of the core, that is made of gold, silver, copper or aluminum, or that is primarily composed of one component of these materials; and a cladding layer that covers the first and second planar surfaces and the outside metal clad.