Children with mental retardation have a high vulnerability to exposure to diseases such as Covid-19. Special interventions are needed to increase the knowledge of mentally retarded children so that they can practice handwashing skills with soap to minimize the transmission of Covid-19 and other diseases. One method that can be applied in the intervention of handwashing with soap is the drill method with flashcard media. This study aims to examine the effect of the flashcard-based drill method intervention on increasing the ability of mentally retarded children to wash their hands with soap. This study uses a Quasi-Experimental design. The planned design is a one-group before and after intervention design. Based on the results of the bivariate test, it is known that there is a significant effect of flashcard-based drill method education on improving handwashing skills with soap in mentally retarded children, Samatiga District, West Aceh Regency. Research clearly shows that the flashcard-mediated drill method intervention has an effect on increasing the knowledge of mentally retarded children so that they are able to practice handwashing behavior with soap so as to minimize the risk of contracting Covid-19 and other bacteria.