The Ministry of Construction's Notification 1441 (2000) on "Verification Method for Egress Safety from a Fire Floor" is composed of a set of prescribed characteristic input values for fire load density, occupant density and so on, coupled with simplified formula to calculate fire and egress behavior. By combining them with building design variables such as room area and ceiling height, nominal escape time margin is calculated. To clarify the degree of safety implemented in the verification method, the stochastic variability in input values and uncertainties in calculation formula have been examined. Based on existing research and survey results, variability and uncertainty are expressed in terms of probability density functions. This work has clarified that : (1) Two variables (fuel load density and occupant density) are recognized as type A variables which contains inevitable stochastic variation. Six variables (walking velocity, specific flow rate, time to start escape, fire growth rate over combustible contents, fire growth rate over lining materials and time to smoke filling) are recognized as type B variables, which contain knowledge uncertainties due to incompleteness of prediction method. (2) The coefficients of variation are large in both type A and type B variables ranging 13 to 235 %. There is a need to reduce uncertainties associated with type B variables. (3) The partial safety factors vary in the range of-0.45 to 4.97. There is a possibility to rearrange the partial safety factors to obtain better balance between variables.