Those detained were attending a traditional condolence gathering for the dead bomber inside a mosque in the Ipekyolu district of the eastern mainly-Kurdish city of Van, the official Anatolia news agency reported.
The militant group which claimed the attack, the Kurdish Freedom Falcons (TAK), had identified the bomber as a Turkish Kurd from Van named Abdulbaki Somer with the nom-de-guerre Zinar Raperin.
Among those arrested were the bomber's brother, his father and the imam of the mosque, the report said.
Pictures published by the Dogan news agency showed the mosque adorned with pictures of Somer.
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A local MP for the pro-Kurdish Peoples' Democratic Party (HDP), Tugba Hezer, was also reportedly at the gathering.
Prosecutors have opened a criminal investigation and will seek to have her parliamentary immunity removed, several reports said.
Prime Minister Ahmet Davutoglu denounced her presence at the gathering as "treachery" and called on the HDP to take a tough stance against her.
"Taking part in a condolence ceremony for a suicide bomber, who spilt blood, commemorating him with respect, is the greatest treachery," he said in parliament.
Ruling party lawmakers accuse the HDP of being the political wing of outlawed Kurdistan Workers Party (PKK) rebels but the faction insists it is an independent entity and condemns terrorism.
The Turkish authorities initially said the suicide bomber was a Syrian citizen but later acknowledged Somer was the likely attacker, while insisting he had spent time in northern Syria.