Idaea purpurea is a moth of the family Geometridae first described by George Hampson in 1891.

[1] It is found in India, Sri Lanka,[2] Taiwan,[3] the Andaman Islands, Peninsular Malaysia and Borneo.

The adult has dull yellow wings with forewing facies and purple-grey banding.

Male has broad yellowish costal zone to the hindwing.

Host plants of caterpillar include Shorea species.