The flux‐density distribution and its stability in the mixed state of type II superconductors in the presence of a stationary longitudinal magnetic field are considered in the connection with the critical conduction current and the longitudinal magnetization. It is believed that the theory similates reasonably well the behavior of the superconductors. It is found that the flux pinning by imperfections in the superconductors becomes ineffective in the longitudinal field because of the induced helical vibrations of pinned flux lines.