[en] The peculiarities of the use of the optical method for investigation of strong ionizing shock waves (ISW) are considered. Given are the comparative results of using the methods of the multiframe high-speed interferometry, shadow and Schlieren photographing for diagnostics of the shock waves forming under spherical irradiation of target by emission from the ''Kalmar'' high-power nine-channel laser installation. It is found, that in determining the ISW front position the use of the Schlieren photographing results in a greater accuracy in comparison with the rest methods. It is expedient to use the quantitative methods together with the Schlieren photographing for determining the ISW front parameters. The shadow photographing is advisable to apply as the qualitative method as well as for the holographic ISW investigation