The scanning permanent magnet method for measuring the critical current density in a high-temperature superconducting (HTS) film has been reproduced numerically. For this purpose, a numerical code has been developed for analyzing the time evolution of a shielding current density in an HTS film with a crack. The results of computations show that the attractive force F-r and repulsive one F-a are observed near the endpoints of the crack when the symmetry axis of the magnet approaches the crack. In addition, the both forces, F-r and F-a, have the maximum value only when the magnet is located above the crack. This means that the crack size and position can be estimated by using the scanning method. (C) 2013 The Authors. Published by Elsevier B.V.