A heating device comprising: a heater including a base and a plurality of resistive heat generators arranged on the base in an arrangement direction, separated from each other, and forming a heat generation area, the heater having a separation area that includes an entire gap between neighboring ones of the plurality of resistive heat generators in the arrangement direction; a rotator; and a pressure rotator configured to press the rotator, the pressure rotator including a first region and a second region, the second region including a position corresponding to the separation area, the second region facing the heater in a part of a range from a center position of the separation area to a center position of the heat generation area, the second region having an outer diameter increasing in a direction from the center position of the heat generation area toward an end of the heat generation area, and the first region nearer to a position being on the pressure rotator and facing the center position of the heat generation area than the second region, the first region having an outer diameter increasing at an increasing rate smaller than an increasing rate of the outer diameter of the second region in the direction from the center position of the heat generation area toward the end of the heat generation area, wherein the pressure rotator has a boundary point (21d2) between a position being on the pressure rotator and facing the center position of the separation area and an end of the pressure rotator opposite the second region with respect to the position being on the pressure rotator and facing the center position of the separation area, and wherein in a part of a range from the boundary point (21d2) to the end of the pressure rotator, an outer diameter of the pressure rotator increases at an increasing rate in a direction from the boundary point (21d2) to the end of the pressure rotator, the increasing rate in the part being smaller than the increasing rate of the outer diameter of the second region. a heater including a base and a plurality of resistive heat generators arranged on the base in an arrangement direction, separated from each other, and forming a heat generation area, the heater having a separation area that includes an entire gap between neighboring ones of the plurality of resistive heat generators in the arrangement direction; a rotator; and a pressure rotator configured to press the rotator, the pressure rotator including a first region and a second region, the second region including a position corresponding to the separation area, the second region facing the heater in a part of a range from a center position of the separation area to a center position of the heat generation area, the second region having an outer diameter increasing in a direction from the center position of the heat generation area toward an end of the heat generation area, and the first region nearer to a position being on the pressure rotator and facing the center position of the heat generation area than the second region, the first region having an outer diameter increasing at an increasing rate smaller than an increasing rate of the outer diameter of the second region in the direction from the center position of the heat generation area toward the end of the heat generation area, wherein the pressure rotator has a boundary point (21d2) between a position being on the pressure rotator and facing the center position of the separation area and an end of the pressure rotator opposite the second region with respect to the position being on the pressure rotator and facing the center position of the separation area, and wherein in a part of a range from the boundary point (21d2) to the end of the pressure rotator, an outer diameter of the pressure rotator increases at an increasing rate in a direction from the boundary point (21d2) to the end of the pressure rotator, the increasing rate in the part being smaller than the increasing rate of the outer diameter of the second region. the second region including a position corresponding to the separation area, the second region facing the heater in a part of a range from a center position of the separation area to a center position of the heat generation area, the second region having an outer diameter increasing in a direction from the center position of the heat generation area toward an end of the heat generation area, and the first region nearer to a position being on the pressure rotator and facing the center position of the heat generation area than the second region, the first region having an outer diameter increasing at an increasing rate smaller than an increasing rate of the outer diameter of the second region in the direction from the center position of the heat generation area toward the end of the heat generation area, wherein the pressure rotator has a boundary point (21d2) between a position being on the pressure rotator and facing the center position of the separation area and an end of the pressure rotator opposite the second region with respect to the position being on the pressure rotator and facing the center position of the separation area, and wherein in a part of a range from the boundary point (21d2) to the end of the pressure rotator, an outer diameter of the pressure rotator increases at an increasing rate in a direction from the boundary point (21d2) to the end of the pressure rotator, the increasing rate in the part being smaller than the increasing rate of the outer diameter of the second region.