Does plantiff have to answer counter claim?

Yes, the plaintiff must respond to a counterclaim filed by the defendant. Typically, this response is called a "reply" and must address the allegations and claims made in the counterclaim. Failing to respond may result in the court treating the counterclaim as admitted, which can have significant legal consequences for the plaintiff. The specific rules and timelines for responding can vary by jurisdiction, so it's important for the plaintiff to be aware of the applicable rules.