Abstract: The apparatus is useful for monitoring integrity of casings, tubings, and other tubular strings in oil and gas wells. An apparatus for defectoscopy of downhole casings includes several units in a housing. An electromagnetic field generation unit generates excitation pulse of a specified amplitude and duration. It includes an exciter coil containing a core made a high magnetic permeability material. A pick-up sensor unit includes an integral pick-up coil and radial pick-up coils mounted around the exciter coil winding. Each pick-up coil has a U-shaped core with poles directed perpendicularly to the surveyed pipe surface and having a center line parallel to the center line of the exciter coil winding. A data control, acquisition, and processing unit includes operational amplifiers with variable amplification factors and analog-to-digital converters (ADCs) that transmit signals from the pick-up coils to software for casing defect analysis.