An image forming apparatus comprising: a main body casing having an upper side and a lower side during operation of the image forming apparatus, wherein a direction from a rear side of the main body casing to a front side of the main body casing is perpendicular to a direction from the lower side to the upper side; a fixing unit accommodated in the main body casing and including a heating member configured to thermally fix a developer image on a recording sheet, and a pressing member disposed opposite to the heating member at a position diagonally upward and rearward of the heating member and configured to convey the recording sheet while the recording sheet is nipped between the heating member and the pressing member; a sheet ejection opening formed in the main body casing at a position frontward of the heating member such that the recording sheet conveyed out from the fixing unit is ejected outside the main body casing through the sheet ejection opening; an exhaust opening formed in the main body casing at a position rearward of the heating member such that air heated in the fixing unit is discharged outside the main body casing through the exhaust opening; a first wall provided inside the main body casing at a position, which is during operation of the image forming apparatus above the heating member and the pressing member, wherein a lower surface of the first wall is configured to guide the air heated in the fixing unit towards the exhaust opening; and an uneven portion provided on the first wall and configured to restrain a dew droplet condensed on the lower surface of the first wall from running down along the first wall; characterized in that the first wall is configured to extend diagonally downward and frontward, and the uneven portion is formed at a position rearward of a front end portion of the pressing member. a main body casing having an upper side and a lower side during operation of the image forming apparatus, wherein a direction from a rear side of the main body casing to a front side of the main body casing is perpendicular to a direction from the lower side to the upper side; a fixing unit accommodated in the main body casing and including a heating member configured to thermally fix a developer image on a recording sheet, and a pressing member disposed opposite to the heating member at a position diagonally upward and rearward of the heating member and configured to convey the recording sheet while the recording sheet is nipped between the heating member and the pressing member; a sheet ejection opening formed in the main body casing at a position frontward of the heating member such that the recording sheet conveyed out from the fixing unit is ejected outside the main body casing through the sheet ejection opening; an exhaust opening formed in the main body casing at a position rearward of the heating member such that air heated in the fixing unit is discharged outside the main body casing through the exhaust opening; a first wall provided inside the main body casing at a position, which is during operation of the image forming apparatus above the heating member and the pressing member, wherein a lower surface of the first wall is configured to guide the air heated in the fixing unit towards the exhaust opening; and an uneven portion provided on the first wall and configured to restrain a dew droplet condensed on the lower surface of the first wall from running down along the first wall; characterized in that the first wall is configured to extend diagonally downward and frontward, and the uneven portion is formed at a position rearward of a front end portion of the pressing member.