A waveguide type optical device comprising: at least one input channel waveguide formed on a waveguide substrate; an input slab waveguide connected to the input channel waveguide; an arrayed waveguide formed with a plurality of channel waveguides connected to the input slab waveguide; a polarization dependence eliminating means provided on the arrayed waveguide; an output slab waveguide connected to the arrayed waveguide; a temperature compensating means that is provided on the input slab waveguide, on the output slab waveguide, on the arrayed waveguide on the input slab waveguide side of the polarization dependence eliminating means, or on the arrayed waveguide on the output slab waveguide side of the polarization dependence eliminating means, and compensates for temperature dependence of an optical path length difference among the channel waveguides of the arrayed waveguide; and at least one output channel waveguide connected to the output slab waveguide, wherein the polarization dependence eliminating means eliminates polarization dependence of each channel from the input slab waveguide to the output slab waveguide, characterized in that, when ΔL" represents an asymmetric correction length to be used by the polarization dependence eliminating means to correct an inter-channel difference in length from the input slab waveguide to the polarization dependence eliminating means on the input slab waveguide side of the polarization dependence eliminating means, an asymmetric correction length to be used by the polarization dependence eliminating means to correct an inter-channel difference in length from the output slab waveguide to the polarization dependence eliminating means on the output slab waveguide side of the polarization dependence eliminating means is -ΔL", and the following equation is satisfied: ΔLʺ = - A × ΔLʹ / 2 where ΔL' represents an inter-channel difference in length of an inserted portion of the temperature compensating means, and A represents a value obtained by dividing birefringence of the input slab waveguide, the output slab waveguide, or the arrayed waveguide on which the temperature compensating means is placed, by birefringence of the arrayed waveguide. at least one input channel waveguide formed on a waveguide substrate; an input slab waveguide connected to the input channel waveguide; an arrayed waveguide formed with a plurality of channel waveguides connected to the input slab waveguide; a polarization dependence eliminating means provided on the arrayed waveguide; an output slab waveguide connected to the arrayed waveguide; a temperature compensating means that is provided on the input slab waveguide, on the output slab waveguide, on the arrayed waveguide on the input slab waveguide side of the polarization dependence eliminating means, or on the arrayed waveguide on the output slab waveguide side of the polarization dependence eliminating means, and compensates for temperature dependence of an optical path length difference among the channel waveguides of the arrayed waveguide; and at least one output channel waveguide connected to the output slab waveguide, wherein the polarization dependence eliminating means eliminates polarization dependence of each channel from the input slab waveguide to the output slab waveguide, characterized in that, when ΔL" represents an asymmetric correction length to be used by the polarization dependence eliminating means to correct an inter-channel difference in length from the input slab waveguide to the polarization dependence eliminating means on the input slab waveguide side of the polarization dependence eliminating means, an asymmetric correction length to be used by the polarization dependence eliminating means to correct an inter-channel difference in length from the output slab waveguide to the polarization dependence eliminating means on the output slab waveguide side of the polarization dependence eliminating means is -ΔL", and the following equation is satisfied: ΔLʺ = - A × ΔLʹ / 2 where ΔL' represents an inter-channel difference in length of an inserted portion of the temperature compensating means, and A represents a value obtained by dividing birefringence of the input slab waveguide, the output slab waveguide, or the arrayed waveguide on which the temperature compensating means is placed, by birefringence of the arrayed waveguide.