Magnetization loss of Bi-2223/Ag tapes was measured with several types of pick-up coils to study the influence of pick-up coil configuration and sample length on the measured losses, Magnetic flux distributions in tapes were calculated numerically by the finite element method to obtain their AC losses, The numerical and experimental losses were compared with each other to clarify the nature of the measured AC losses. In the parallel magnetic field, the height of the pick up coil must equal or be larger than the tape height for the accurate loss measurement, In the perpendicular magnetic field, the size of the pick up coil must be much larger than the tape width for the accurate loss measurement. If the length of the sample tape is short, the measured loss contains coupling loss component at commercial frequencies, while the filaments are almost decoupled in DC measurement by SQUID magnetometer.