An attempt was made to synthesize an adsorbent by the photoinduced grafting of acrylic acid (AA) onto polypropylene nonwoven fabrics using benzophenone (BP) as a photosensitizer in a CH3OH/H2O medium. As the BP concentration was increased, the graft yield was increased up to a specific value and then decreased, and the effect of AA concentration showed the same tendency. It was also found that the graft yield increased with the reaction time and temperature. The amounts of ammonia adsorbed onto polypropylene nonwoven fabrics grafted with AA (PP-g-AA) were dependent on the graft yield, adsorption time, and ammonia gas pressure. The adsorption capacity of PP-g-AA was 5.86 mmol/g at the graft yield of 116.6%, which was much higher than that of active carbon or silica gel.