We investigated the nonlinear optical properties of ReSe2. First, we measured the nonlinear absorption coefficient and the nonlinear refractive index of a ReSe2 thin film using open-aperture (OA) and closed-aperture (CA) Z-scan techniques. ReSe2 was shown to possess both saturable absorption and self-defocusing properties. The nonlinear absorption coefficient of ReSe2 was measured to be (5.67±0.35)×103cm/GW, and its nonlinear refractive index was (2.81±0.13)×10 2cm2/GW at 1560 nm. Next, a fiberized saturable absorber (SA) based on ReSe2 was fabricated with a side-polished fiber platform and was tested as an ultrafast mode-locker capable of producing femtosecond pulses operating at a wavelength of 1560 nm. The estimated modulation depth and saturation power are ～3.9% and ～42W, respectively, for the transverse electric mode, while they are ～2.4% and ～53W for the transverse magnetic mode. Using the prepared SA, stable soliton pulses with a temporal width of ～862fs were produced from an erbium-doped fiber ring cavity. To the best of the authors’ knowledge, this is the first demonstration of using a ReSe2-based SA for femtosecond mode-locked pulse generation.