In this article the problem on the motion of a charged particle in the field of frequency-modulated electromagnetic wave and in the external uniform static magnetic field has been analyzed; the exact solutionsof the corresponding equations have been presented. This problem is of great importance to study the interaction of high-intensity laser pulses with solid targets and to develop practically multifrequency lasers and the laser-modulation emission technology. The formulae for the mean kinetic energy of a relativistic charged particle as a function of initial conditions, electromagnetic wave amplitude, wave intensity and its polarization parameter were obtained. The different cases of initial conditions of a charged particle motion and of a wave polarization were investigated. The obtained results can be put to use when studying the hightemperature plasma formed on the surface of the target and when searching for new modes of laser-plasma interaction.