Elachista sagittifera is a moth in the Elachistidae family. It was described by Philpott in 1927. It is found in New Zealand. The wingspan is about 11.5 mm. The forewings are white, the base of the costa to one-sixth narrowly fuscous. There is a whitish-ochreous stripe along the costa, broadest on the basal half. There is an ochreous stripe along the fold to two-fifth and an ochreous-fuscous stripe above the fold, as well as a fuscous stripe along the dorsum to the tornus. The hindwings are dark fuscous.