Gasification is a key technology for efficient use of solid fuels. The moisture with a high content in lignite can be used during gasification reactions. Because a fluidized bed gasifier usually operates at a low temperature, a high concentrate of tar is entrained with generated syngas. Tar discharged to outside of the gasifier is processed by methods, for instance, high-temperature reformers, scrubbers, or adsorption by activated carbon, to reform tar to gas. These processes bring about an increase in running costs. The traditional evaluation index of tar is concentration in syngas, for example, "g/m(3)N". It is necessary to elucidate the details of tar composition to optimize a gasification system; it is insufficient with only a concentration. The purpose of this study is to clarify the tar components generated by gasification conditions (steam gasification and pyrolysis) of lignite at 1123 K using a laboratory-scale fluidized bed gasifier in detail, by a combination of gas chromatograph mass spectrometry (GC/MS) and field desorption mass spectrometry (FD-MS). As the results, it was found that tar contained polycyclic aromatic hydrocarbons (PAHs) with a molecular weight range of 150-600 mainly in both conditions. By steam reforming, the tar concentration in steam gasification was lower than that in pyrolysis. However, the main tar components were almost the same in both conditions.