Thermohydraulic behavior of electrically conducting turbulent flow in a pipe with full-length twisted tape insertion under magnetic field is investigated numerically. When the magnetic field is applied to a normal turbulent pipe flow, velocity fluctuation is damped and heat transfer performance is decreased. As for the turbulent pipe flow with a twisted tape, however, decrease in Nusselt number due to the applied magnetic field is less than that in the normal pipe, because the helical flow structure made by the twisted tape is hardly suppressed under the magnetic field. Therefore, it can be concluded that the twisted tape is effective scheme for heat transfer enhancement under the magnetic field.