The announcement comes just weeks before the new election that was called since Yoon caused political chaos by introducing martial law in the country.
South Korea is going to the polls on June 3 to choose a successor to Yoon. Voices have been raised within his party, the conservative PPP, about excluding the former president since the largest opposition party's candidate – liberal Lee Jae-Myung – is pulling ahead in the polls.
"I'm leaving the PPP today", Yoon now writes on Facebook and urges voters to support the party's official candidate Kim Moon-Soo.
Yoon Suk-Yeol was impeached on April 4, after having suddenly declared a state of emergency with martial law last year.
