To allow an ocular training tool to have a function of determining visual acuity and a means for confirming a result.

A plurality of landmarks each to be a target are arranged at a prescribed interval in a string (2) of about 1-5m. One end of the string is fixed to a part of a building, or the like, so as to be horizontally even with eyes. Then, ocular exercise is performed by putting the other end (5) on the upper part of a nose being the center of both the eyes. Thus, it is called a block string. At least one of the landmarks has a disk shape (6), where at least more than one Landolt rings (8) are arranged on at least one plane part (7), and is slidably arranged on the string.