A pollen analysis was made for the samples obtained from the Lower part of the Osaka group at Senriyama, Osaka. The results are as follows; 1. Of the genera which are of the Tertiary type, Metasequoia, Ginkgo, Liquidambar, and Pseudolarix(?) disappeared in horizons ranging Senriyama tuff to Ma2. The horizons of extinction are Senriyama tuff for Pseudolarix(?), Ma0 for Ginkgo, and a nonmarie layer below Ma2 for Liquidambar, and Ma2 for Metasequoia. 2. The Lower part of the Osaka group is divided into five zones which are named A, B......, E zones from below in the present paper. The C zone corresponds to the Lower Metasequoia sub-zone of OD-1 Core (TAI, 1966), the D zone the upper Metasequoia sub-zone and the E zone the Fagus zone. 3. The D zone is considered to be of the age of extinction of Matasequoia. Accompanied by a decrease in Metasequoia, Cryptomeria began to increase at the top of the C zone; Metasequoia died out in Ma2 layer and was replaced by Cryptomeria. 4. The pollen flora of nonmarine beds found in the D zone suggests the Lowering of temperature. Therefore it is considered that in the D zone (Upper Metasequoia sub-zone) nonmarine beds are deposits of the age of lowering in temperature whereas marine beds were deposited in warmer age.