Cardanol-formaldehyde resin was synthesized from a reaction of formaldehyde and cardanol separated from decarboxylated cashew nut shell liquid in the presence of sodium hydroxide and characterized by infrared spectroscopy and nuclear magnetic resonance spectroscopy. The physical properties of asphalt, modified through reaction (5 h, 150 ํC) with cardanol-formaldehyde resin (CF), maleic anhydride (MA), maleic resin (MR) and paraformaldehyde (PF), were investigated using dynamic shear rheometry and penetrometer. The results of physical properties indicated that the asphalt-CF reaction products were found to have reduced temperature sensitivity (increased penetration index) to more elastic in character (decreased delta) compared to asphalt cement, asphalt-MA, asphalt-MR and asphalt-PF products. The asphalt-CF products gave rutting resistance for pavement to 64 ํC. This work showed that CF was a non-inert additive and improved basic physical properties.