Wave propagation on uniformly sloped beaches is a canonical coastal engineering topic that has been studied extensively in the past few decades. However, most of these studies treat beaches as solid boundaries even though they are often made of porous materials, such as sediment and vegetation. Permeable beaches struck by tsunami-like waves have not been adequately investigated. It is expected that the degree of permeability plays a crucial role in mitigating the impact of the wave. This study examines solitary wave run-ups on sandy beaches using an incompressible smoothed particle hydrodynamics (ISPH) model. The permeability of the beach is considered to be directly related to the diameter of its constituent sand particles. To obtain a satisfactory pressure field, which cannot be achieved using the original ISPH algorithm, the source term of the Poisson pressure equation has been modified based on a higher-order source-term expression. Flows within the porous medium are computed in the same framework as those outside the porous medium. In the current model, no transition zone is needed at the boundary of the porous structure. The wave-attenuation effect of the porous medium is discussed, with a particular focus on the relationship between the run-up height and grainsize.