The naming of Hitachinaka City comes from Hitachinaka Port (located in the old Katsuta City) and the name of this port has the old provincial name Hitachi in front of Naka Port to distinguish from Nakaminato Fishing Port; in this way Hitachinaka City followed the naming method of avoiding the duplication of city name when the new city name was needed to be created at the time Katsuta City and Nakaminato City merged.
ひたちなか市は勝田市と那珂湊市の合併に際して重複回避に準じた命名法則を取っているが、那珂湊漁港と区別するため旧国名を冠した常陸那珂港（旧勝田市に所在）が名称の由来となっている。