A liquid drop ejecting head includes a cavity section which is formed by laminating a plurality of plates including at least first and second manifold plates adjacent to each other in a laminating direction. Each of the first and second manifold plates includes an opening. The openings overlap with each other when viewed in the laminating direction. At least one of the openings includes: a first opening which extends in the first direction and serves as a common liquid chamber; a second opening which is adjacent to the first opening and serves as a supply path; and a partitioning portion disposed between the first opening and the second opening.