The authorities should release Nasiruddin Elan, the group's director, who was denied bail and jailed in Dhaka on November 6, Human Rights Group said.
Adilur Rahman Khan, the group's secretary, is also facing charges.
It said adding that the cases were brought against the activists for their reporting on human rights abuses by government security forces, and therefore violate freedom of expression.
"The Bangladeshi authorities should be investigating the security force abuses that Odhikar reported on, not filing cases that violate rights against the messengers," said Brad Adams, Asia director at Human Rights Watch.
Both are charged under section 54 of the Code of Criminal Procedure and section 57 of the Information and Communication Technology Act (ICT Act), Odhikar told Human Rights Watch.