Yes, dark matter is believed to have mass. In fact, the presence of mass is one of the key reasons why scientists propose the existence of dark matter. Dark matter is a hypothetical form of matter that does not interact with light or other electromagnetic radiation, making it invisible and difficult to detect directly.
The evidence for the existence of dark matter comes from various astrophysical and cosmological observations, such as the rotation curves of galaxies, the motion of galaxies within galaxy clusters, and the large-scale structure of the universe. These observations indicate that there is more mass in the universe than can be accounted for by the visible matter (stars, gas, and dust) alone.
The gravitational effects of this unseen mass, which we call dark matter, explain the observed motions and structures. While we cannot directly observe or interact with dark matter using electromagnetic radiation, its gravitational influence on visible matter provides strong evidence for its existence and indicates that it must have mass.
The exact nature of dark matter and its composition are still unknown. Various theoretical models propose different types of particles that could make up dark matter, such as weakly interacting massive particles (WIMPs) or axions. However, to date, no direct detection of dark matter particles has been confirmed.