The loading frequency dependence of fatigue crack growth in the near-threshold region in SUS304 steel were investigated using constant K_<max> test method at 350℃, 550℃ and 650℃ in a vacuum. Loading frequency was changed from 30 Hz to 3 Hz and vice versa 30 Hz, and crack growth rates at f=30 and 3 Hz were compared. It was found that crack growth behavior in the region below the conventional threshold value was dependent on the loading frequency. Investigations of the fractal properties of their fatigue fracture surfaces were performed. It was found that the measured values of fractal dimensions of fracture surface tested at 650℃ in a vacuum were larger than those of fracture surface tested at 350℃ and 550℃ in a vacuum.