Bacteria is classified as a member of the Monera Kingdom because it is a unicellular organism with a prokaryotic cell.
The cytoplasm is surrounded by a rigid cell wall. Amitosis is the division of cells.

The plastid, mitochondria, endoplasmic reticulum, and other cytoplasmic organelles are all missing, leaving only the ribosome. That is why bacteria is classified as a member of the Monera Kingdom.