To characterize the prey composition of frogs inhabiting the Tottori Sand Dunes, we examined the stomach contents of 141 individuals of five species (Dryophytes japonicus, Rana japonica, Pelophylax nigromaculatus, Fejervarya kawamurai, and Lithobates catesbeianus). Stomach contents were obtained from 86 frogs. A total of 356 individuals of prey were obtained from 50 P. nigromaculatus. Species in the orders Coleoptera and Araneae were frequently observed in the diets of P. nigromaculatus, but the most common prey item was Labidura riparia in the order Dermaptera (Class Hexapoda); its numerical percentage and frequency of occurrence percentage were 26.7% and 74%, respectively. Labidura riparia was also the most common prey item in the diets of the other four frog species, although the sample sizes for the other species were small. These findings suggest that when P. nigromaculatus migrated to new habitats (e.g., coastal habitats in our study), the immigrant frogs may be able to change its diet in response to the change in available prey items in the habitats. The plastic prey consumption in response to variations in prey resources might be an important factor for its survival in new habitats.