There is provided a waveguide connection structure for connecting a waveguide 2 formed on a multilayer dielectric substrate 1 and a waveguide 4 formed on a metal substrate 3. The waveguide connection structure includes a choke structure having a rectangular conductor pattern 7, a conductor opening 8, and a dielectric transmission path 9. The rectangular conductor pattern 7 is formed around the waveguide 2 in the multilayer dielectric substrate 1, and has a dimension of about λ/4 (λ: a free-space wavelength of a signal wave) from an E-side edge of the waveguide 2. The conductor opening 8 is formed at a predetermined position on the conductor pattern 7 between the end of the conductor pattern 7 and the E-side edge of the waveguide 2. The dielectric transmission path 9 is connected to the conductor opening 8, and is formed in the multilayer dielectric substrate in the layer direction to have a length of about λg/4 (λg: an in-substrate effective wavelength of the signal wave) with a closed end. Even when a gap is formed between the multilayer dielectric substrate and the metal substrate, it is possible to achieve the connection characteristics of the waveguides with lower leakage and lower loss of signals at the connection area of the waveguides, and to prevent the degradation of the connection characteristics that occurs due to the resonance in the higher order mode when the waveguides are misaligned.