Locustella amnicola Sakhalin grasshopper warbler (Helopsaltes amnicola), is a species of grass warbler in the family Locustellidae; it was formerly included in the "Old World warbler" assemblage.

This small passerine bird breeds on Sakhalin, the southern Kuril Islands and Hokkaido.

It is a species found in lowland and coastal regions, nesting in forests or thickets.

The adult has an unstreaked olive-brown back, uniformly grey breast and buff underparts, with unmottled dull orange undertail coverts.

The song is a short phrase, loud and distinctive; nothing like the insect-like reeling of European Locustella species, and more musical than that of Pallas's grasshopper warbler.