A high-energy heat treatment method of heating a surface layer of a workpiece made of steel for implementing quench-hardening, said heat treatment method comprising the steps of: measuring a hot section temperature corresponding to a temperature of a portion in which the temperature rises most in said workpiece; measuring a cold section temperature corresponding to a temperature of a portion in which the temperature rises least in said workpiece; adjusting the temperature of said workpiece; and determining quenching timing for said workpiece, said step of adjusting the temperature of said workpiece including the steps of heating said workpiece by high energy heating, by which a workpiece is not heated through the heated atmosphere but a part of the workpiece is directly heated, and controlling heating of said workpiece by said high energy heating based on said hot section temperature, in said step of determining quenching timing for said workpiece, said quenching timing being determined based on said hot section temperature and said cold section temperature such that said steel forming said workpiece exhibits a predetermined solid-dissolved state of carbon on a TTA diagram in entire said workpiece, and said TTA diagram being derived by a calculation formula obtained by conducting a regression analysis of a result of an experiment performed in advance for examining a relation between said solid-dissolved state of carbon in said steel and each of a heating temperature and a heating time of said steel, wherein said calculation formula is obtained using a formula described below as a regression formula: M = M 0 exp − kt n where k = Aoexp (-E/RT), M: area ratio of carbide (%), the area ratio of carbide being measured by electron microscopy analysis performed on a cross-section of a test piece, Mo: area ratio of carbide before heat treatment (%), t: heating time (second), Ao, E: constant determined by material, R: gas constant, and T: temperature. measuring a hot section temperature corresponding to a temperature of a portion in which the temperature rises most in said workpiece; measuring a cold section temperature corresponding to a temperature of a portion in which the temperature rises least in said workpiece; adjusting the temperature of said workpiece; and determining quenching timing for said workpiece, said step of adjusting the temperature of said workpiece including the steps of heating said workpiece by high energy heating, by which a workpiece is not heated through the heated atmosphere but a part of the workpiece is directly heated, and controlling heating of said workpiece by said high energy heating based on said hot section temperature, in said step of determining quenching timing for said workpiece, said quenching timing being determined based on said hot section temperature and said cold section temperature such that said steel forming said workpiece exhibits a predetermined solid-dissolved state of carbon on a TTA diagram in entire said workpiece, and said TTA diagram being derived by a calculation formula obtained by conducting a regression analysis of a result of an experiment performed in advance for examining a relation between said solid-dissolved state of carbon in said steel and each of a heating temperature and a heating time of said steel, wherein said calculation formula is obtained using a formula described below as a regression formula: M = M 0 exp − kt n where k = Aoexp (-E/RT), M: area ratio of carbide (%), the area ratio of carbide being measured by electron microscopy analysis performed on a cross-section of a test piece, Mo: area ratio of carbide before heat treatment (%), t: heating time (second), Ao, E: constant determined by material, R: gas constant, and T: temperature.