Thermoluminescence (TL) age determination was carried out for 40 lava samples, one quartz vein and 8 samples from collapsed materials (pyroclastic/debris flow and avalanche deposits) in the Unzen area. The TL growth curve method was used for quartz phenocrysts and vein quartz of the above rocks to determine the ages within the maximum error of 30%. The Unzen volcanic rocks consist of the basal volcanic rocks and the overlying three groups (Takadake, Kusenbudake, and Fugendake in order of formation). The basal volcaniclastic rocks range in age from 230 to 180 ka, overlapping with the age of Takadake group (290 to 180 ka), and with the lower subgroup of Kusenbudake. The Kusenbudake group is classified into the lower subgroup in the western part (190 to 130 ka) and the upper subgroup in the eastern part (130 to 99 ka). The activity of the Fugendake group occurred from 86 to 55 ka in the periphery, resulting in the formation of lower subgroup, and concentrated in the center around 15 to 10 ka, upper subgroup. The age of Mayuyama in the Fugendake group which was under debate among many researchers was determined as 2.7 to 3.4 ka. This supports the stratigraphic relation of Mayuyama. Based on the TL age determination results and chemical compositions (U, Th and K contents) of the bulk rocks, the supplying sources of collapsed materials were identified successfully. The Kinugasayama volcanic rocks are characterized by low U content and high Th content, while those of Fugendake and Mayuyama are characterized by high levels of U and Th contents.