A heater for an image forming apparatus comprising: a substrate comprising: a base having a shorter-side and a longer-side of the heater, the shorter-side direction being perpendicular to the longer-side direction; and a step forming unit protruded from the base in a direction perpendicular to the longer-side and the shorter-side directions, wherein the step forming unit extends in the longer-side direction of the base; and surface which includes a first surface corresponding to an upper surface of the step forming unit, and a second surface that is disposed on both sides of the first surface in the shorter-side direction of the heater and positioned lower than the first surface, wherein the normal of the upper surface is perpendicular to the longer-side and the shorter-side directions, and a heat generating layer having ends in the shorter-side direction and disposed on only a central region in the shorter side direction of the upper surface of the step forming unit, an electrode layer configured to drive the heat generating layer; wherein the electrode layer is disposed on two sides of the step forming unit in the shorter-side direction of the base; wherein the electrode layer comprises a first electrode layer and a second electrode layer; wherein the first electrode layer is provided on the second surfaces of the base; and part of the second electrode layer is provided on ends of the upper surface of the step forming unit in the shorter side direction, and part of the second electrode layer is deposited on each end of the heat generating layer in the shorter-side direction of the heater and connected to the each end; and the electrode layer further comprises a connecting unit extending in the direction perpendicular to the longer-side and the shorter-side directions, the connecting unit connecting between an end of the first electrode layer positioned closer to the center of the base in the shorter-side direction and an end of the second electrode layer positioned closer to an end of the base in the shorter-side direction, a first protective layer disposed on the heat generating layer and the second electrode layer; and a second protective layer disposed on the first electrode layer; wherein the first protective layer and the second protective layer have a top surface, respectively, and the top surface of the latter is positioned lower than the top surface of the former. a substrate comprising: a base having a shorter-side and a longer-side of the heater, the shorter-side direction being perpendicular to the longer-side direction; and a step forming unit protruded from the base in a direction perpendicular to the longer-side and the shorter-side directions, a base having a shorter-side and a longer-side of the heater, the shorter-side direction being perpendicular to the longer-side direction; and a step forming unit protruded from the base in a direction perpendicular to the longer-side and the shorter-side directions, wherein the step forming unit extends in the longer-side direction of the base; and surface which includes a first surface corresponding to an upper surface of the step forming unit, and a second surface that is disposed on both sides of the first surface in the shorter-side direction of the heater and positioned lower than the first surface, wherein the normal of the upper surface is perpendicular to the longer-side and the shorter-side directions, and a heat generating layer having ends in the shorter-side direction and disposed on only a central region in the shorter side direction of the upper surface of the step forming unit, an electrode layer configured to drive the heat generating layer; wherein the electrode layer is disposed on two sides of the step forming unit in the shorter-side direction of the base; wherein the electrode layer comprises a first electrode layer and a second electrode layer; wherein the first electrode layer is provided on the second surfaces of the base; and part of the second electrode layer is provided on ends of the upper surface of the step forming unit in the shorter side direction, and part of the second electrode layer is deposited on each end of the heat generating layer in the shorter-side direction of the heater and connected to the each end; and the electrode layer further comprises a connecting unit extending in the direction perpendicular to the longer-side and the shorter-side directions, the connecting unit connecting between an end of the first electrode layer positioned closer to the center of the base in the shorter-side direction and an end of the second electrode layer positioned closer to an end of the base in the shorter-side direction, a first protective layer disposed on the heat generating layer and the second electrode layer; and a second protective layer disposed on the first electrode layer; wherein the first protective layer and the second protective layer have a top surface, respectively, and the top surface of the latter is positioned lower than the top surface of the former.