A developing device , comprising: a developing chamber including an opening portion ; a developing sleeve (13-1) located in the developing chamber and partially exposed to an outside of the developing chamber through the opening portion ; a magnetic member (13-2) located inside the developing sleeve (13-1), the magnetic member (13-2) including a separating pole (S2) and a receiving pole (S3), the separating pole (S2) being located on a downstream side of the opening portion based on a rotating direction of the developing sleeve (13-1) to separate a developing agent from the developing sleeve (13-1), and the receiving pole (S3) being located on a downstream side of the separating pole (S2) to attach the developing agent to the developing sleeve (13-1); and a magnet located between an inner wall of the developing chamber and the magnetic member (13-2), the magnet facing a region between the separating pole (S2) and the receiving pole (S3), and the magnet having a same magnetic polarity as the separating pole (S2) and the receiving pole (S3), wherein the inner wall includes a first air discharge hole to discharge air inside the developing chamber , the first air discharge hole including a filter to filter the developing agent, and wherein the magnet is located: adjacent the first air discharge hole , between the filter and the magnetic member (13-2), and adjacent to an upstream-side end of the first air discharge hole based on the rotating direction of the developing sleeve (13-1), wherein the developing device further comprises a second air discharge hole located on a downstream side edge of the opening portion based on the rotating direction of the developing sleeve (13-1) and located outside an effective image region in a longitudinal direction of the developing sleeve (13-1), and an air discharge path connecting the first air discharge hole to the second air discharge hole . a developing chamber including an opening portion ; a developing sleeve (13-1) located in the developing chamber and partially exposed to an outside of the developing chamber through the opening portion ; a magnetic member (13-2) located inside the developing sleeve (13-1), the magnetic member (13-2) including a separating pole (S2) and a receiving pole (S3), the separating pole (S2) being located on a downstream side of the opening portion based on a rotating direction of the developing sleeve (13-1) to separate a developing agent from the developing sleeve (13-1), and the receiving pole (S3) being located on a downstream side of the separating pole (S2) to attach the developing agent to the developing sleeve (13-1); and a magnet located between an inner wall of the developing chamber and the magnetic member (13-2), the magnet facing a region between the separating pole (S2) and the receiving pole (S3), and the magnet having a same magnetic polarity as the separating pole (S2) and the receiving pole (S3), wherein the inner wall includes a first air discharge hole to discharge air inside the developing chamber , the first air discharge hole including a filter to filter the developing agent, and wherein the magnet is located: adjacent the first air discharge hole , between the filter and the magnetic member (13-2), and adjacent to an upstream-side end of the first air discharge hole based on the rotating direction of the developing sleeve (13-1), wherein the developing device further comprises a second air discharge hole located on a downstream side edge of the opening portion based on the rotating direction of the developing sleeve (13-1) and located outside an effective image region in a longitudinal direction of the developing sleeve (13-1), and an air discharge path connecting the first air discharge hole to the second air discharge hole . <EOS>