Rhagastis albomarginatus is a moth of the family Sphingidae. It is known from the Himalaya, China, Taiwan, Burma, Sumatra, Java and Borneo. The forewing upperside has the first and third postmedian lines reduced to a series of prominent vein dots, the second postmedian line is very weak or absent, There is an inconspicuous and diffuse pale patch and a similar but less marked pale area. The pale band is reduced to an ill-defined patch near the anal angle. The fringe is weakly dentate with white with brown vein spots. The costal edge is at least partly creamy white. The hindwing underside has a small black discal spot.