Moving picture encoding apparatus

An encoding circuit (1) encodes an input image. A thinning-out decision unit (2) determines whether or not a picture needs to be thinned out. A dummy picture storage device (4) stores a dummy picture. A dummy picture is encoded data in which all the blocks refer to the same picture, motion vectors of all the blocks are zero, and none of the blocks has prediction residual information. A reference picture selection unit (5) selects a reference picture from among a plurality of referenceable pictures. A header generating unit (7) generates a header to be added to a dummy picture. In the header, the selected reference picture is assigned to an index specifying a reference picture for the dummy picture.