Compact X-band multi-parameter doppler weather radars (Model: WR-2100 Furuno Electric Co.) were installed in August 2017 at six sites near Sakurajima, Kirishima, Satsuma-Iwojima, Kuchinoerabujima and Suwanosejima volcanoes, in Souther Kyushu, Japan. The X-band radars detected eruption plumes of Shinmoedake eruptions of Kirishima volcano from October 2017 to April 2018 and Minamidake eruptions of Sakurajima volcano. We estimated the eruption plume height of the eruption on November 13, 2017 at Sakurajima as 4 km by using the radar reflectivity, although the visual plume height was unknown due to bad weather. By comparing the radar reflectivity of the 2017 and 2018 eruptions of Shinmoedake with the plume heights by visual observation, we accumulated the basic data for establishing a method for estimating eruption plume heights using weather radars. For example, the plume height of the continuous eruption on April 5, 2018 is estimated to be 9 km by the weather radar, which is roughly equal to the height by the geostationary meteorological satellite Himawari-8.