A method of producing a press-formed product, comprising: a steel plate heating step of heating a steel plate to 950°C or more, a hot forging step of using a first press apparatus to forge the steel plate to form a varying-thickness steel plate by repeatedly beating the steel plate, and a hot stamping step of using a second press apparatus different from the first press apparatus, the hot stamping step comprising press-working to form the varying-thickness steel plate into a press-formed product by means of press tooling of the second press apparatus, and cooling the press-formed product inside the press tooling, the method of producing a press-formed product further comprising: after the hot forging step and before the hot stamping step, a varying-thickness steel plate heating step of heating the varying-thickness steel plate to a temperature that is not less than an A c3 transformation point and not more than an "A c3 transformation point + 150°C", the method of producing a press-formed product further comprising: after the hot forging step and before the varying-thickness steel plate heating step, a cooling step of water-cooling the varying-thickness steel plate to room temperature, wherein the steel plate has a thickness of around 2.0 to 6.0 mm, wherein: the varying-thickness steel plate includes a portion having a large thickness and a portion having a small thickness, and a ratio "t1/t2" between a plate thickness t1 of the portion having a large thickness and a plate thickness t2 of the portion having a small thickness is more than 1.8. a steel plate heating step of heating a steel plate to 950°C or more, a hot forging step of using a first press apparatus to forge the steel plate to form a varying-thickness steel plate by repeatedly beating the steel plate, and a hot stamping step of using a second press apparatus different from the first press apparatus, the hot stamping step comprising press-working to form the varying-thickness steel plate into a press-formed product by means of press tooling of the second press apparatus, and cooling the press-formed product inside the press tooling, the method of producing a press-formed product further comprising: after the hot forging step and before the hot stamping step, a varying-thickness steel plate heating step of heating the varying-thickness steel plate to a temperature that is not less than an A c3 transformation point and not more than an "A c3 transformation point + 150°C", the method of producing a press-formed product further comprising: after the hot forging step and before the varying-thickness steel plate heating step, a cooling step of water-cooling the varying-thickness steel plate to room temperature, wherein the steel plate has a thickness of around 2.0 to 6.0 mm, wherein: the varying-thickness steel plate includes a portion having a large thickness and a portion having a small thickness, and a ratio "t1/t2" between a plate thickness t1 of the portion having a large thickness and a plate thickness t2 of the portion having a small thickness is more than 1.8. after the hot forging step and before the hot stamping step, a varying-thickness steel plate heating step of heating the varying-thickness steel plate to a temperature that is not less than an A c3 transformation point and not more than an "A c3 transformation point + 150°C", the method of producing a press-formed product further comprising: after the hot forging step and before the varying-thickness steel plate heating step, a cooling step of water-cooling the varying-thickness steel plate to room temperature, wherein the steel plate has a thickness of around 2.0 to 6.0 mm, wherein: the varying-thickness steel plate includes a portion having a large thickness and a portion having a small thickness, and a ratio "t1/t2" between a plate thickness t1 of the portion having a large thickness and a plate thickness t2 of the portion having a small thickness is more than 1.8. after the hot forging step and before the varying-thickness steel plate heating step, a cooling step of water-cooling the varying-thickness steel plate to room temperature, wherein the steel plate has a thickness of around 2.0 to 6.0 mm, wherein: the varying-thickness steel plate includes a portion having a large thickness and a portion having a small thickness, and a ratio "t1/t2" between a plate thickness t1 of the portion having a large thickness and a plate thickness t2 of the portion having a small thickness is more than 1.8.