Dynamics of pulsed laser ablation of Si is studied in various kinds of ambients. It is found that the shape of droplets on the films prepared by pulsed laser ablation is influenced by both the ambient pressure and the distance between the target and the substrate. Oxidation of ablated Si species in O-2 ambient is also controlled by these two parameters. Oxidation of Si in low-pressure O-2 ambient is enhanced by the addition of high-pressure He, which is possibly explained by the reaction due to enhanced collision in the shock front formed in high-pressure ambient.