A fusing device, comprising: a first roller configured to rotate about its axis; a second roller configured to rotate about its axis and to form a fusing nip part (N, N1, N2, Na, Nb) together with the first roller; an adjustment mechanism (72, 75, 60) configured to change posture of the first roller or the second roller between first posture and second posture to adjust a nip pressure of the fusing nip part (N, N1, N2, Na, Nb), the adjusting mechanism (72, 75, 60) setting the first or second roller (31 or 32) in the first posture to allow between the first roller and the second roller 32) press contact by a first pressure, and setting the first or second roller (31 or 32) in the second posture to allow between the first roller and the second roller 32) press contact by a second pressure which is reduced from the first pressure; a separation member arranged downstream of the fusing nip part (N, N1, N2, Na, Nb) in a direction of rotation of the first roller and including a plate-shaped member extending in an axial direction of the first roller, a turning mechanism (431, 363, 45) configured to turn the separation member about an axis parallel to the axial direction of the first roller, the turning mechanism (431, 363, 45) turning the separation member whereby a tip end of the plate-shaped member approaches a peripheral surface of the first roller when the posture of the first or second roller (31 or 32) is changed from the second posture to the first posture; an abutting member mounted on each opposite end of the plate-shaped member of the separation member and configured to abut, when the first or second roller (31 or 32) is in the first posture, on the peripheral surface of the first roller in a vicinity of each opposite end of the first roller to form a gap between the tip end of the plate-shaped member and the peripheral surface of the first roller; and an isolation mechanism configured to allow the abutting member to abut on the peripheral surface of the first roller when the first or second roller (31 or 32) is in the first posture; the fusing device characterized in that the isolation mechanism is configured to separate the abutting member from the peripheral surface of the first roller at a time at which the posture of the first or second roller (31 or 32) is changed from the first posture to the second posture. a first roller configured to rotate about its axis; a second roller configured to rotate about its axis and to form a fusing nip part (N, N1, N2, Na, Nb) together with the first roller; an adjustment mechanism (72, 75, 60) configured to change posture of the first roller or the second roller between first posture and second posture to adjust a nip pressure of the fusing nip part (N, N1, N2, Na, Nb), the adjusting mechanism (72, 75, 60) setting the first or second roller (31 or 32) in the first posture to allow between the first roller and the second roller 32) press contact by a first pressure, and setting the first or second roller (31 or 32) in the second posture to allow between the first roller and the second roller 32) press contact by a second pressure which is reduced from the first pressure; a separation member arranged downstream of the fusing nip part (N, N1, N2, Na, Nb) in a direction of rotation of the first roller and including a plate-shaped member extending in an axial direction of the first roller, a turning mechanism (431, 363, 45) configured to turn the separation member about an axis parallel to the axial direction of the first roller, the turning mechanism (431, 363, 45) turning the separation member whereby a tip end of the plate-shaped member approaches a peripheral surface of the first roller when the posture of the first or second roller (31 or 32) is changed from the second posture to the first posture; an abutting member mounted on each opposite end of the plate-shaped member of the separation member and configured to abut, when the first or second roller (31 or 32) is in the first posture, on the peripheral surface of the first roller in a vicinity of each opposite end of the first roller to form a gap between the tip end of the plate-shaped member and the peripheral surface of the first roller; and an isolation mechanism configured to allow the abutting member to abut on the peripheral surface of the first roller when the first or second roller (31 or 32) is in the first posture; the fusing device characterized in that the isolation mechanism is configured to separate the abutting member from the peripheral surface of the first roller at a time at which the posture of the first or second roller (31 or 32) is changed from the first posture to the second posture.