This utility model relates to the field of magnetic flaw detection, to devices for non-destructive testing of pipelines, and, in particular, to a magnetic system for an in-pipe flaw detector. The technical effect of the claimed utility model consists in decreasing mutual influence of main belts of magnetic modules and improving uniformity of magnetic field distribution in circumferential and longitudinal directions. The magnetic system for transverse magnetization having fixed magnetic modules and designed for an in-pipe flaw detector consists of two main and four additional belts of magnetic modules, which are arranged on two magnetic conductors connected with a non-magnetic insert. Each magnetic module consists of permanent magnets and wire brushes that transfer a magnetic flux into the pipeline wall. Magnetic modules that are adjacent to each other in a belt have opposite directions of a magnetic field in an interpolar space. The main poles of magnetic modules are angularly offset relative to each other. The additional belts of magnetic modules are arranged at the edges of the main belts of magnetic modules, two additional magnetic modules being arranged between the belts of main magnetic modules and serving for compensating mutual influence of a magnetic field generated by the main magnetic modules and for decreasing non-symmetry of the magnetic field, which is caused by close location of the main poles. Each additional belt of magnetic modules serving for correcting non-symmetry of the field is angularly offset relative to a main magnetic belt.