Nonlinear absorption measurements at 800 nm and 400 nm in single wavelength high reflection (HR) dielectric mirrors were performed, according to the ISO 11551 standard by pulse, gradient and exponential absorption evaluation methods, using pulsed, diode pumped femtosecond laser system with pulse duration {\~}130 fs. Pulsed laser output at 1kHz repetition rate had 1 W and 0.36 W average power at 800 nm and 400 nm, respectively. The HR mirrors were made of ZrO2 and SiO2 layers. The beam was focused into the mirror, and changing the beam power by step attenuator, it was possible to evaluate nonlinear absorption at different intensities up to intensity close to damage threshold. The nonlinear absorptance for 400 nm pulses at the femtosecond pulse intensity 0.8 TW/cm2 was 0.48 \% and {\~}20 times exceeded the nonlinear absorptance for the 800 nm pulses.