The experimental model of edge-focusing (EF) wiggler has been fabricated to evaluate its performance rigorously with the magnetic field measurement. It is a 5-period planar wiggler with an edge angle of 2° and a period length of 60 mm. The magnetic field is measured using Hall probes at four different wiggler gaps. The field gradient of the EF wiggler is derived from the magnetic field measured at several transverse positions along the longitudinal position. It is experimentally confirmed that a high field gradient of 1.0 T/m is realized, as designed, along the beam axis. We found that the small orientation errors of the Hall probes and of the linear stages for them lead to large errors in the measured magnetic field. We analyzed the relation between the orientation errors of the measurement system and the measured magnetic field or field gradient using a model magnetic field of the EF wiggle. We corrected the measurement magnetic field based on this analysis. Detailed description of error sources and corrections are given in this paper.