Abstract: An ink jet printing apparatus has a casing which is divided into upper and lower regions by a dividing wall. In the lower region, between the dividing wall and the base of the casing is an ink circulation unit. A pump of the of the ink circulation unit passes ink from a main ink container to a tube and hence to a printing head of the apparatus. The ink circulation unit may have a filter for filtering the ink before it passes to the printing head, and also have a secondary ink container and a solvent container for containing ink and solvent which are passed to the main container as they are used up during printing. Access to the containers and the filter, which need periodic replacement, is via an access cover in the casing. The access cover is at the front of the casing so that it can be used by an operator when the printing apparatus is in its normal position. Above the dividing wall is a circuit board unit which controls the ink circulation unit, and also the printing head.