We carried out magnetic and neutron diffraction measurements in order to study spontaneous and induced spin-reorientation (SR) transitions of the "easy axis-easy plane" type in poly- and single-crystalline samples of hexagonal Tm2Fe17. We determined the temperature dependence of lattice parameters and the angle between the c axis and magnetic moments of Tin and Fe sublattices. We found that the SR transition was accompanied by a large change (about 20%) in the magnetization anisotropy of the Tm subsystem. An external magnetic field of mu(0)H(cr) = 5 T along the hard-magnetization direction is enough to cause a field-induced SR transition at 4.2 K, and, with increasing temperatures, H-cr decreases. At low temperatures, the spontaneous magnetization along the easy-magnetization direction is found to be smaller at low temperatures than that along the hard-magnetization direction. Based on this result, we propose that there also exists a magnetization anisotropy also for the Fe subsystem.