An image forming apparatus is disclosed that includes a fixing device including: a fixing member; and a pressure member configured to be pressed against the fixing member in order to form a nip portion, wherein a sheet configured to be fed into the nip portion in order to fix unfixed toner image thereon; a compressor configured to supply compressed air; a nozzle configured to be disposed at an outlet side of the nip portion and to blast the compressed air to an adhered portion of the sheet to the fixing member; and a controller configured to correct open-time of the nozzle based on image forming condition and to control number of times that the compressed air is blasted to the sheet in accordance with length of corrected open-time, wherein the open-time of the nozzle is determined in accordance with basis weight of the sheet.