Right now it looks like department is just a single field with one value. How can it hold a List.
You might have a Department table that in the Employee table has a FK id that maps to a record in the Department table. In that case you mappings should be ManyToOne from Employee to Department. but you cna also have a bi-directional association in Department that has a List of Employees.
But it looks like your table design doesn't support that and that your mappings doesn't show that.
For Employee to Department association look at this
doc http://www.hibernate.org/hib_docs/annotations/reference/en/html/entity.html#d0e1177 For Department to List of Employee associations look at this doc
http://www.hibernate.org/hib_docs/annotations/reference/en/html/entity.html#entity-mapping-association-collections And it is possible to have a self-referencing table, and map that in itself.
Mark