A dynamic load measurement method for a rotary forging device, characterized by: the rotary forging device comprising: a pressing die support part (13, 15, 27, 29) capable of supporting any one selected from a forming pressing die and a measuring pressing die to be rotatable about a reference axis (α) and to freely rotate about an axis of rotation (β) inclined at a predetermined angle with respect to the reference axis (α); a support table configured to support an object to be pressed disposed at a position facing a pressing die supported by the pressing die support part (13, 15, 27, 29) in a direction of the reference axis (α); and a load application apparatus configured to apply a load in the direction of the reference axis (α) to the object to be pressed by pressing the pressing die supported by the pressing die support part (13, 15, 27, 29) against the object to be pressed supported by the support table on the basis of relative movement of the pressing die support part (13, 15, 27, 29) and the support table in the direction of the reference axis (α), the method comprising: supporting the measuring pressing die by the pressing die support part (13, 15, 27, 29), supporting a measuring shaft member by the support table and linearly guiding the measuring shaft member in the direction of the reference axis (α), the measuring shaft member being an object to be pressed and being disposed coaxially with the reference axis (α), and measuring an actual load, by the load application apparatus, in the direction of the reference axis (α) applied to the measuring shaft member using a load cell disposed between the support table and the measuring shaft member in a state in which the measuring pressing die is pressed against the measuring shaft member while the measuring pressing die is rotated about the reference axis (α). the rotary forging device comprising: a pressing die support part (13, 15, 27, 29) capable of supporting any one selected from a forming pressing die and a measuring pressing die to be rotatable about a reference axis (α) and to freely rotate about an axis of rotation (β) inclined at a predetermined angle with respect to the reference axis (α); a support table configured to support an object to be pressed disposed at a position facing a pressing die supported by the pressing die support part (13, 15, 27, 29) in a direction of the reference axis (α); and a load application apparatus configured to apply a load in the direction of the reference axis (α) to the object to be pressed by pressing the pressing die supported by the pressing die support part (13, 15, 27, 29) against the object to be pressed supported by the support table on the basis of relative movement of the pressing die support part (13, 15, 27, 29) and the support table in the direction of the reference axis (α), a pressing die support part (13, 15, 27, 29) capable of supporting any one selected from a forming pressing die and a measuring pressing die to be rotatable about a reference axis (α) and to freely rotate about an axis of rotation (β) inclined at a predetermined angle with respect to the reference axis (α); a support table configured to support an object to be pressed disposed at a position facing a pressing die supported by the pressing die support part (13, 15, 27, 29) in a direction of the reference axis (α); and a load application apparatus configured to apply a load in the direction of the reference axis (α) to the object to be pressed by pressing the pressing die supported by the pressing die support part (13, 15, 27, 29) against the object to be pressed supported by the support table on the basis of relative movement of the pressing die support part (13, 15, 27, 29) and the support table in the direction of the reference axis (α), the method comprising: supporting the measuring pressing die by the pressing die support part (13, 15, 27, 29), supporting a measuring shaft member by the support table and linearly guiding the measuring shaft member in the direction of the reference axis (α), the measuring shaft member being an object to be pressed and being disposed coaxially with the reference axis (α), and measuring an actual load, by the load application apparatus, in the direction of the reference axis (α) applied to the measuring shaft member using a load cell disposed between the support table and the measuring shaft member in a state in which the measuring pressing die is pressed against the measuring shaft member while the measuring pressing die is rotated about the reference axis (α). supporting the measuring pressing die by the pressing die support part (13, 15, 27, 29), supporting a measuring shaft member by the support table and linearly guiding the measuring shaft member in the direction of the reference axis (α), the measuring shaft member being an object to be pressed and being disposed coaxially with the reference axis (α), and measuring an actual load, by the load application apparatus, in the direction of the reference axis (α) applied to the measuring shaft member using a load cell disposed between the support table and the measuring shaft member in a state in which the measuring pressing die is pressed against the measuring shaft member while the measuring pressing die is rotated about the reference axis (α).