The rigidity of railway roadbed and subgrade is evaluated with K_30-value obtained by the plate loading test. However, the plate loading test requires long periods of time and large-scale reaction equipment. To propose a simple and quick method to evaluate the rigidity of railway roadbed and subgrade, therefore, we tested a method that uses an FWD (Falling Weight Deflectometer). As a result, we obtained a conclusion that it is possible to evaluate the rigidity of roadbed and subgrade by the method of using an FWD.