Antiplanes sanctiioannis is a species of sea snail, a marine gastropod mollusk in the family Pseudomelatomidae, the turrids.

The shell is clothed with a smooth, thickish, olive epidermis.

The shell is covered with very narrow spiral striae and incremental flexuous stripes.

The narrow outer lip has a wide sinuation above the middle.

[2] This marine species occurs off he Pacific coast of northern Honshu, Japan; also in the Bering Sea.