
Maj General Anan Srihiran, commander of Metropolitan Police Division 1, said police would further interrogate the PAD leaders.
The suspects were released on Bt100,000 bail each, with three senators also acting as guarantors for them, police said.
Their surrender came a day after the Appeals Court withdrew arrest warrants issued for the PAD leaders on charges of treason, a possibly capital offence.
Two of the nine PAD leaders arrested earlier on the same charges, Chamlong Srimuang and Chaiwat Sinsuwong, were freed on Thursday when the court made the ruling.
The remaining seven PAD leaders showed up at Nang Lerng Police Station about 10am.
The station is not far from Government House, which has been seized by protesters affiliated with the PAD.
Six of the leaders, Sondhi Limthongkul, Pipop Thongchai, Somsak Kosaisuk, Suriyasai Katasila, Amorn Amornratananont and Therdpoom Chaidee, surrendered at 9.45am.
Democrat Party MP Somkiart Pongpaiboon arrived at 10.20am and waived his parliamentary immunity.
Police read out the lesser charges of illegal assembly and inciting unrest before booking the six.
The PAD leaders had refused to surrender until the Appeals Court revoked the treason charge against them, which they said was unjustified. It carries the death penalty or a life sentence.