Flat plate slamming problem involves complicated interactions between the solid or deformable structure with the air-water flow. In order to investigate this problem, we carried out a series of dropping tests using flat elastic plates with different aspect ratios in a water tank while measuring pressure on the plates and observe the flow field. Both the longitudinal edges of each plate are kept close to the tank walls and so deflection of the plate and associated flow may be considered as two-dimensional (2D). Time histories of the pressure and its maximum values are reported in this paper. Based on the experimental results, the maximum values and durations of the pressure measured at the center of the plates are compared with empirical formulae in literatures.