There is provided a multi-cored fiber array for optical communication which has high dimensional accuracy, can easily be prepared by machining, and is low in cost. There is also provided a fiber array for optical communication which can reduce the necessary amount of an adhesive used for fixing optical fibers to a substrate. The fiber array for optical communication comprises: a substrate for inserting optical fibers therein; and a press plate for pressing and fixing the inserted optical fibers. The substrate has a plurality of grooves into which the optical fibers are to be inserted. The accuracy of the center-to-center dimension between the grooves adjacent to each other is within .+-.0.5 .mu.m, and the degree of parallelization in the groove length direction between the grooves adjacent to each other is within .+-.0.1 degree.