In this paper influence of incorrect calibration of AD5933 electrical impedance analyzer on errors in measurements was investigated. AD5933 is developed in the form of electronic integrated circuit by the Analog Devices. This device is very popular in the field of Structural Health Monitoring based on electromechanical impedance method. Electromechanical impedance method relies on measurements of electrical impedance of piezoelectric transducer bonded to the structure. Due to electromechanical coupling of piezoelectric transducer mechanical resonances of the structure can be seen in the electrical impedance characteristics of piezoelectric transducer. In order to properly measure electrical impedance mentioned devices must be calibrated using calibration resistor. In this research influence of wrongly selected calibration resistor value on the measurement results was interrogated. Measurements conducted with AD5933 were compared with measurements realized using professional electrical impedance analyzer HIOKI IM3570. Research was related to simple supported beam made out of aluminium alloy with piezoelectric transducer in the form of disc. Measurements were taken for referential state as well as for few states with artificial introduced damage in the form of notch.