We measured fine particles in the diesel (DF) or bio-diesel fuel (131317) combustion exhaust generated by a diesel power generator (YDG5500B Yanmer) at two different loads (0 and 1500 W). After the dilution of exhausts to 300 times, fine particles were collected with quartz fiber filter and the size-distributions were measured with Scanning Mobility Particle Sizer. Ionic components, organic and elemental carbon, and polycyclic aromatic hydrocarbon (PAHs) were analyzed with lonchromatograph, Thermal Optical Carbon Analyzer, and high-performance liquid chromatograph-fluorescence detector respectively. The chemical compositions and number-size distributions of fine particles were observed at the different combination of DF or BDF and miner, or synthetic lubricant. In the size distributions of diesel and bio-diesel exhaust particles at the different load modes, respective size distribution under low loa condition showed lower mass concentration than high load condition. When using BDF, more organic carbon (OC) was emitted than when using DF without considerable change on number-size distribution of particles, while more elemental carbon (EC) and PAHs were emitted when using DF. In the combination BDF and synthetic lubricating oil, the lowest concentration of EC, total PAHs and respective PAH were observed in the exhaust. These results suggest that 6 exhaust quality from BDF combustion can improve when replacing mineral lubricating oil to synthetic lubricating oil.