Seiko Obonai

{{Short description|Japanese shot putter (1940–2023)}}

{{use dmy dates|date=January 2018}}

{{Infobox sportsperson

| name = Seiko Obonai

| full_name =

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| nationality = Japanese

| sport = Athletics

| event = Shot put

| birth_date = {{birth date|1940|2|16|df=yes}}

| birth_place = Ninohe, Iwate, Japan

| death_date = {{death date and age|2023|3|6|1940|2|16|df=yes}}

| death_place = Tokyo, Japan

| height =

| weight =

}}

{{Nihongo|Seiko Obonai|小保内 聖子|Obonai Seiko|16 February 1940 – 6 March 2023}}[https://www.iwate-np.co.jp/obituary/2432 椛沢　聖子さん] {{in lang|ja}} was a Japanese track and field athlete. She competed in the women's shot put at the 1964 Summer Olympics.{{cite Sports-Reference |url=https://www.sports-reference.com/olympics/athletes/ob/seiko-obonai-1.html |archive-url=https://web.archive.org/web/20200417211503/https://www.sports-reference.com/olympics/athletes/ob/seiko-obonai-1.html |url-status=dead |archive-date=17 April 2020 |title=Seiko Obonai Olympic Results |access-date=7 January 2018}}