On October 14, 1705, Nagashige followed Ienobu TOKUGAWA who entered the nishi-no-maru (west building) of Edo-jo castle and was transferred to the position of nishi-no-maru roju and his salary was increased by 10,000 koku which made the total amount of his salary in rice 60,000 koku
宝永2年(1705年)8月27日、江戸城西の丸に入った徳川家宣に従って西の丸老中に転じ、1万石加増で都合6万石を知行する。