Polystyrene absorbs radon thermodynamically as well as liquid aromatic solvents. We had proposed a new radon measurement using this phenomenon. The measurement, APDLSAbsorptive Polymer Dissolved Liquid Scintillation Counting, is a very easy radon measurement.APDLSfilm that absorbed radon is dissolved in liquid scintillator, and the radioactivity of radon can be measured by liquid scintillation counter. The absorption factor of radon is the radon concentration ratio betweenAPDLSfilm and water. We showed the absorption factor of theAPDLSfilm in table. Radon concentration ofAPDLSfilm divided by the factor is the radon concentration of sample water. This measurement is practicable to radon measurement for environmental research, and has many merits as follows. (1) APDLSmeasurement has no chemical hazard, and is easy to treat. (2) APDLSfilm is easily dissolved in toluene scintillator, and maintains ideal condition for liquid scintillation. (3) The measurement error was less than 5%, and the detection limit was 0.05 Bq Rn/kg water. (4) APDLSfilm is available from Kyoritsu Chemical Check Lab. Co.