Platinum nanoparticles have industrial application, for example in catalysis, and are used in consumer products such as cosmetics and supplements. Therefore, among the many nanoparticles, platinum is one of the more accessible nanoparticles for consumers. Most platinum nanoparticles that are used in cosmetics and supplements which have an anti-oxidant activity are modified particles. However, the cellular influences of pristine platinum nanoparticles are still unclear, although it has been reported that platinum nanoparticles induce oxidative stress. In this study, we investigated the cellular influences induced by pure pristine platinum nanoparticles. Platinum nanoparticles of 100% purity were dispersed in a cell culture medium and stable medium dispersion was obtained. The platinum nanoparticle medium dispersion was applied to two kinds of cultured cells, A549 and HaCaT cells, and the cellular influences were examined. Cell viability (MTT assay), cell proliferation (clonogenic assay), apoptosis induction (caspase-3 activity), intracellular ROS level (DCFH assay), and lipid peroxidation level (DPPP assay) were measured as markers of cellular influences. Transmission electron microscope observation showed cellular uptake of platinum nanoparticles. However, the platinum nanoparticles did not drive any markers. It is known that some metal oxide nanoparticles such as NiO and CuO show severe cytotoxicity via metal ion release. Compared with these toxic nanoparticles, the platinum nanoparticles used in this study did not release platinum ions into the culture media. These results suggest that the physically and chemically inactive cellular influences of platinum nanoparticles are small.