Disclosed is a grain conveying apparatus using air, the apparatus efficiently collecting foreign materials while moving grains upward to a position at which the grains are easily fed into a grain processing machine by using the suction force air, and preventing shock so as to prevent damage to the grains. The grain conveying apparatus using air, according to the present invention, comprises: a grain supply hopper for accommodating the grains; a conveyer pipe for guiding the grains supplied from the grain supply hopper and the air flowing in from an external air inlet such that the grains, by means of the air suction force, and the air are moved together; a grain discharge pipe connected to the end of the conveyer pipe; a separation pipe for separating the grains and the foreign materials, the separation pipe comprising a horizontal part connected to the grain discharge pipe and a downwardly curved part for dropping the grains; a rotary valve connected to the lower part of the curved part of the separation pip
