To provide a tag attached sheet capable of inhibiting erroneous information from being written into a tag adjacent to a tag targeted to be written even when a positioning interval between adjacent tags is made to be narrower.

The erroneous information can be inhibited from being written into a second tag 22 which is adjacent to a first tag 12 targeted to be written even when a positioning interval between the first tag 12 and the adjacent second tag 22 is made to be narrower, by a tag mounting sheet 10 comprising the first tag 12 to be attached on a mat 10A and for transmitting and receiving electronic information by a radio wave, and the second tag 22 to be mounted on the mat 10A so as to be adjacent to the first tag 12, and for transmitting and receiving the electronic information by the radio wave in which an antenna 26 is extended into a direction crossing to an extension direction of an antenna 16 of the first tag 12 in a plane view.