Abstract: A display apparatus of magnetic flux density for detecting an internal crack of a metal or a shape of the metal includes a three-dimensional magnetic flux focusing unit installed near the metal, for concentrating magnetic flux generated by the metal, a magnetic flux density measurement unit installed near the magnetic flux focusing unit, for measuring changes in magnetic flux density concentrated by the magnetic flux focusing unit, and a display unit electrically connected with the magnetic flux measurement unit, for real-time displaying and storing changes in the magnetic flux density.