Two-dimensional pattern reverse Monte Carlo method is applied to investigate structural changes of silica particle filler in uniaxially elongated rubber. We calculated three-dimensional conformations of spherical silica particles using a series of two-dimensional patterns of structure factors during elongation. The structure factors we used are inter polated from experimentally observed structure factors for the elongation ratio epsilon = 0.0, 0.5, 1.0, and 1.5. To make a continuous motion of particles, we set the elongation ratio with small interval Delta epsilon = 0.001. It is found that the structural change of the particles seem to be reliable at least for small epsilon regions because spurious motions like the Brownian motions are not observed.