We show that THz absorptance of metals can be significantly increased by structuring the surface of metals with 1D array of parallel grooves produced by a scanning femtosecond laser beam. In our study, we enhance the absorptance of titanium up to 51% at wavelength of 70 mu m (4.2 THz) even without optimization of the surface structure. This our finding shows that femtosecond laser surface structuring technology is suitable for creating highly absorptive metal materials for a variety of terahertz and submillimeter waves applications including terahertz spectroscopy, THz sensing, THz stealth technology, and space astronomy.