The strength of blast wave (or shock wave) in air is a very important factor that has to be considered in the design and construction of the magazine for explosive materials from the point of view on security range for humans and specific objects in case of accidentally caused explosion. Measurements on the strength of blast wave have been carried out during the past several decades and have provided the fundamental data on the propagation of blast wave in air, but the experiments have mostly been conducted under conditions of the free-air or surface burst explosions. In order to understand the blast wave propagation in a practical underground magazine explosion, both laboratory and field tests have been doing using simulated magazine to investigate the blast waves generated from the assembled explosive in it. This paper will give numerical analysis on the blast wave propagation from explosion in a model magazine that has been conducted by field tests. The numerical tool is MARS2D, which is of Eulerian formulation with the employment of a high precision and low diffusion scheme popularly known as CIP. Another feature of this code is on the determination of pressure of mixtures cell that can simply deal with many substances in one cell by an explicit method instead of the traditional iteration procedures used by many numerical codes. The computed blast waves are compared with those obtained from experiments. The accuracy of numerical predictions is discussed.