The crystal structure and composition of the Co-Ni-Fe films has been analyzed, and the effect of the deposition rate on the coefficient dB/dH of conversion of a weak magnetic field into the magnetic induction has been established. The presence of oxygen on the film surface indicates the porosity of the Co-Ni-Fe film structure, which is confirmed by the surface roughness. Electrochemical deposition from a chloride electrolyte has demonstrated the possibility of controlling the magnetic properties of the films by improving the deposition technique. The chloride electrolyte with filtration and boric acid, saccharin, and hydrochloric acid additives in a concentration ratio of CCo : CNi : CFe = 1 : 1 : 1 ensures, at a temperature of 70 degrees C, the reproducible electrochemical deposition of the Co-Ni-Fe films with low stresses, a uniform structure, and a high coefficient of conversion of a weak magnetic field into the magnetic induction.