An imaging system with a gloss treatment device includes an endless belt, a heating portion and a pressing portion. The endless belt conveys a medium along a conveyance direction. The heating portion heats the endless belt. The pressing portion presses the endless belt against the heating portion. A nip is formed in a region where the endless belt contacts both of the pressing portion and the heating portion. The nip includes an upstream end and a downstream end in the conveyance direction, and a reference line intersects the upstream end and the downstream end of the nip. The endless belt includes a conveyance portion that is inclined toward the heating portion, in relation to the reference line associated with the nip.