An electric resistance welding operation management device which is a data processing device provided with a CPU, ROM, RAM, a HDD and various interfaces, the data processing device being configured to manage an electric resistance welding operation during manufacture of electric resistance welded steel pipe, in which heat is input to a metal plate, that is being conveyed along a specific conveyance direction and formed into a circular tube shape while pressing side faces of the metal plate with a pair of squeeze rolls (2a, 2b), to weld together two circumferential direction edge portions of the metal plate converging in a V-shape, the electric resistance welding operation management device comprising: an image input means configured to input a plurality of images that are successively captured over a specific duration and each include a Vee convergence region that is a region where the metal plate converges in a V-shape; a first position detection means configured to, based on the images input by the image input means, detect the position of a geometric Vee convergence point that is a geometric intersection point (V 0) of the two circumferential direction edge portions of the metal plate converging in a V-shape; a second position detection means configured to, based on the images input by the image input means, detect the position of a Vee convergence point that is a contact point (V 1) where the two circumferential direction edge portions of the metal plate converging in a V-shape abut each other; a determination means configured to determine whether or not the position of the geometric Vee convergence point detected by the first position detection means and the position of the Vee convergence point (V 1) detected by the second position detection means are present at different positions to each other; characterized in that the device further comprises: a welding point position derivation means configured to, based on each of the plurality of images input by the image input means, derive the position of a welding point, based on acquired data that takes as the position of a welding point the position, out of positions at each point in time within the specific duration, of a slit end at the furthest conveyance direction downstream point of a weld slit, having the Vee convergence point (V 1) as a base point and extending further than the Vee convergence point toward the metal plate conveyance direction downstream side, at the point in time when the slit end is positioned furthest downstream in the conveyance direction; and a heat input control means configured to, if the position of the geometric Vee convergence point and the position of the Vee convergence point are determined by the determination means to be present at different positions to each other, lower a heat input power to the metal plate in cases in which a distance between the position of the welding point derived by the welding point position derivation means and a position corresponding to an installation position of the pair of squeeze rolls (2a, 2b) has become a threshold value, or shorter. a welding point position derivation means configured to, based on each of the plurality of images input by the image input means, derive the position of a welding point, based on acquired data that takes as the position of a welding point the position, out of positions at each point in time within the specific duration, of a slit end at the furthest conveyance direction downstream point of a weld slit, having the Vee convergence point (V 1) as a base point and extending further than the Vee convergence point toward the metal plate conveyance direction downstream side, at the point in time when the slit end is positioned furthest downstream in the conveyance direction; and a heat input control means configured to, if the position of the geometric Vee convergence point and the position of the Vee convergence point are determined by the determination means to be present at different positions to each other, lower a heat input power to the metal plate in cases in which a distance between the position of the welding point derived by the welding point position derivation means and a position corresponding to an installation position of the pair of squeeze rolls (2a, 2b) has become a threshold value, or shorter.