1. An information display system for displaying information comprising: an information display apparatus which includes an imaging unit; and an information provision apparatus; wherein the information display apparatus comprises: a key information acquiring unit which acquires key information corresponding to a subject in a captured image captured by the imaging unit; and a key information transmitting unit which transmits the key information to the information provision apparatus, wherein the information provision apparatus comprises: a reference image storage unit which stores (i) reference images including reference subjects and (ii) scale information of the reference subjects and superimposing information corresponding to the reference images, respectively; and an information providing unit which selects at least one of the reference images based on the key information, and which provides to the information display apparatus (i) the at least one selected reference image and (ii) the scale information and the superimposing information corresponding to the at least one selected reference image; wherein the information display apparatus further comprises: a guide displaying unit which displays guide information based on (i) the scale information corresponding to the at least one selected reference image, and (ii) scale information of the subject in the captured image; an image matching unit which matches the subject in the captured image with the at least one selected reference image in accordance with the displayed guide information; and a superimposed displaying unit which superimposes and displays the superimposing information corresponding to the at least one selected reference image based on a matching result matched by the image matching unit on the captured image.