Generation properties of the soft X-ray from femtosecond laser produced plasma are reported. Table-top-tera watt Ti: Al₂O₃ laser system with a pulse width of 100 fs and a repetition rate of 10 Hz is used in the experiment. Spectra and pulse duration properties of the soft X-ray obtained from fs laser produced various metal plasmas are discussed. The typical soft X-ray spectra for various metal targets with different atomic numbers are experimentally obtained. The minimum pulse duration of 6 ps is measured by X-ray streak camera in the single pulse excitation to the target. As this value is limited by the instrument resolution, the further short pulse duration may be expected. The efficient soft X-ray generation is also demonstrated by adopting the double pulse irradiation to the target. Especially, by using this scheme, Nd doped glass targets generate the large photon number of 10¹¹ photon/(Å· Sr) at 8±0.05 nm. Application of the X-ray produced by femtosecond laser pulse to material science is also reviewed. Preliminary experiment of double resonance reflection spectrum change at near Si L_{2, 3} absorption edge is demonstrated.