Takagi Masanari served as a bushō and daimyō during the Azuchi-Momoyama and Edo periods.  He was the second lord of the Kawachi-Tannan domain in Ōmi Province.  He held the titles of Junior Fifth Rank (Lower) and Chief of Water Provisions.

Masanari was born as the eldest son of Takagi Masatsugu, the first lord of the Tannan domain.  His mother was the adopted daughter of Ōkubo Tadasuke.

From 1598, Masanari served the Tokugawa clan.  At the Second Battle of Ueda in 1600, Masanari joined his father, Masatsugu, to attack Sanada Masayuki.  In 1614, he served valorously at the Winter Campaign of the Siege of Ōsaka and was granted a fief of 1,000 koku in Kazusa Province.  In 1615, during the Summer Campaign, he fought at the gateway to Tennōji and, despite sustaining injuries, contributed to the effort so his fief was increased by another 1,000 koku.  In 1630, upon the death of Masatsugu, Masanari succeeded him.  At this time, he allocated the foregoing 2,000 koku to his eldest son, Takagi Masahiro, and his second son, Takagi Masayoshi.

Owing to his work providing security for Odawara Castle and as the head clerk of writing alcoves, he received an increase of 3,000 koku to his fief in Kazusa and, later, served as the ōbangashira, a role with overall responsibility for security at Edo, Ōsaka, and Nijō castles.

On 3/11 of Kanei 12 (1635), Masanari died at the age of forty-nine and he was succeeded by his eldest son, Masahiro.