A compact millimeter-wave three-pole dual-band bandpass filter (BPF) by using substrate-integrated waveguide (SIW) dual-mode cavities is developed in this paper. The proposed filter consists of three SIW dual-mode cavities, in which the TE₂₀₁ and TE₁₀₂ modes are used to form two passbands. The center frequencies of the two passbands can be readily changed by varying the lengths and/or widths of the SIW cavities. Meanwhile three transmission zeros are produced with appropriate design of the input and output of the SIW cavities, which increase significantly the isolation between the two passbands and their roll-off rate of attenuations. The dual-band BPF filter is designed, fabricated and measured. The measured center frequencies of the two passbands are 26.75GHz and 31.55GHz, respectively. The 3dB-passbands are 26.35-27.15GHz (3%) and 31.29-31.81GHz (1.6%), respectively, with maximum insertion loss of 2.64dB and 4.2dB, respectively, and return loss larger than 12dB in both passbands. A good agreement between the simulated and measured filter characteristics is obtained.