[en] Nonpotential (electromagnetic) drift instabilities, which are caused by α-particles produced in thermonuclear reaction, are investigated theoretically. Several types of instabilities are analyzed; considerable attention is paid to instabilities requiring both α-particle space non-uniformity and magnetic field curvature. It is shown that the earlier developed theory of thermonuclear instabilities has been in complete; it has not taken into consideration instabilities that are most important from the point of view of plasma turbulent transfer across the magnetic field in toroidal traps of tokamak type. Such instabilities are caused by the non-uniformity of α-particle space distribution and the curvature of magnetic field force lines. Instabilities caused by both flight and trapped α-particles are considered. It is shown that there is a number of thermonuclear drift instabilities whose increments depend on the α-particle space grasient and the curvature of magnetic field force lines. Such instabilities are due to the build up of Altven waves by α-particles. Fast magnet oacoustic waves can build up drift wise, when the ratio of α-particle Larmor radius to the plasma non-uniformity dimension is finite. The coefficients of plasma turbulent transfer across the magnetic field are conditined by the instabilities under investigation. It is estimated that they are much greater than the corresponding coefficients of the earlier studied instabilities and comparable with the Bohm diffusion coefficient. Therefore, the above-considered instabilities must be taken into account in the reactor-tokamak theory