(eng): We apply a method of time-dependent Hurst exponent, proposed in the series of papers by Grech and Mazur [Physica A 336, 335 (2004)], Grech and Pamula [Physica A 387, 4299 (2008)] and Czarnecki, Grech and Pamula [Physica A 387, 6801 (2008)], on the stock market of the Czech Republic for a period between 1997 and 2009. Our results support the findings of the authors so that the time-dependent Hurst exponent can give some crucial information before a critical event happens on a market. We also discuss some potentially weak points of the method.