The results of an investigation of the electromagnetic wave polarization, probing high-temperature laser plasma, as well as spatial-temporal structure of the magnetic fields, electron density, current density, and electron drift velocity are presented. To create the plasma, plane massive Al targets were irradiated with the second harmonic of a phoenix Nd laser at intensities up to 5·1014 W/cm2. It was shown that the magnetooptical Faraday effect is the main mechanism responsible for the changing polarization of the probing wave. Magnetic fields up to 0.4 MG with electron densities ∼1020 cm−3 were measured. Analysis of the magnetic field spatial distribution showed that the current density achieved the value ∼90 MA/cm2 on the laser axis. The radial structure of the magnetic field testified to the availability of the reversed current in the laser plasma. The spatial and temporal resolutions in these experiments were equaled to ∼5 µsec and ∼50 psec, respectively.