Abstract: The device has a processor (20) that applies a magnetic field to a measurement subject (2) and after the magnetic field is discontinued, uses an induced electromotive force detector (17) to measure the magnetic fluxes emitted from multiple locations, calculates time constants of transient change of the plurality of magnetic fluxes, and detects the internal structure of the measurement subject (2) from the distribution of the time constants. The processor (20) prompts the induced electromotive force detector (17) to make first measurements at predetermined locations, prompts the induced electromotive force detector (17) to make second measurements at locations rotated by a predetermined angle from the predetermined locations, and based on the internal structure detected by the first measurements and the internal structure detected by the second measurements, estimates the center location of the nugget and/or the diameter of the nugget which has been formed inside the measurement subject (2).

Abstract: The device has a processor (20) that applies a magnetic field to a measurement subject (2) and after the magnetic field is discontinued, uses an induced electromotive force detector (17) to measure the magnetic fluxes emitted from multiple locations, calculates time constants of transient change of the plurality of magnetic fluxes, and detects the internal structure of the measurement subject (2) from the distribution of the time constants. The processor (20) prompts the induced electromotive force detector (17) to make first measurements at predetermined locations, prompts the induced electromotive force detector (17) to make second measurements at locations rotated by a predetermined angle from the predetermined locations, and based on the internal structure detected by the first measurements and the internal structure detected by the second measurements, estimates the center location of the nugget and/or the diameter of the nugget which has been formed inside the measurement subject (2).

Abstract: An extra super multi-story building having one piece of extra super multi-story of about 200 story construction, two pieces of extra super multi-stories of about 150 story construction and one piece of extra super multi-story of about 100 story construction. Each extra super multi-story includes two through four pieces of tower-like super multi-stories of about 50 story construction and of about 50 m in diameter (floor area: about 200 m.sup.2 /story). A sky lobby is provided about every 50 stories connecting the extra super multi-stories. Four shuttle elevators lead from the ground to the sky lobbies, and a sightseeing tower and high-rise garden (sky dome) are provided at the rooftop of the extra super multi-story building. Main facilities such as offices, hotels and residences are arranged in each extra multi-story.