This invention provides a steel pipe material weld zone heating method and apparatus for melting and welding the weld zone of a steel pipe material that during continuous induction heating and welding of moving steel pipe material as the material being heated controls temperature distribution and molten steel shape and weld frequency fluctuation with high accuracy and high efficiency, irrespective of the shape of the heated region of material being heated or the material properties of the material being heated, which comprises a first imaging step in which first imaging means 3 installed opposite an end face weld zone of the steel pipe material is used to detect self-emitted light of the weld zone and output a brightness image, a weld zone temperature distribution computation step in which image processing is performed based on the brightness image and emitted light temperature measurement is applied to compute the plate-thickness direction temperature distribution of the weld zone, a heating control step in which a criterion defined in advance for the relationship between alternating current frequency and plate-thickness direction temperature distribution is used to determine the frequency of the alternating current based on the plate-thickness direction temperature distribution, and a step in which the variable frequency alternating current power supply 1 is used to pass through the steel pipe material 10 alternating current of the frequency determined in the heating control step.