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In order to clarify the fatigue behavior of Ni-base superalloy Udimet 720Li, four point bending fatigue tests of plain specimens were carried out at room temperature. Initiation and propagation behavior of major cracks was observed by plastic replica technique. At extremely early stages of cycling, cracking of TiN particles was generated. Fatigue cracks were always initiated from cracked TiN particles. The growth rate of a small crack can be determined by a term σ^n_al, not by ΔK. The n is a material constant and was 3.6. On the other hand, the statistical characteristics of fatigue behavior were investigated to quantify the scatter in fatigue damage. Namely, the distribution for crack length, microcrack growth life and crack growth rate were analyzed by assuming a Weibull distribution. Moreover, the cracking time and cracking orientation of all the TiN particles were measured. The measurements suggested that the TiN particle were fractured by the principal tensile stress which is related to the variation in local strain around a particle.