The medical-solution administration device (10) advances the cylinder (12), the gasket (34), the pusher body (36) for pushing out the chemical solution (M) from the cylinder (12), and the pusher body (36). An advance mechanism (38), a drive mechanism (39) for driving the advance mechanism (38), a chassis member (24) supporting at least the cylinder (12) and the advance mechanism (38), a cylinder (12), A pusher body (36), an advance mechanism (38), a drive mechanism (39), and a housing (28) for housing the chassis member (24) are provided. The chassis member (24) has a first support portion that supports the distal end surface of the first supported portion of the tubular body (12) and a second support that supports the base end surface of the second supported portion of the advance mechanism (38). And a part.薬液投与装置（１０）は、筒体（１２）と、ガスケット（３４）と、筒体（１２）から薬液（Ｍ）を押し出す押し子本体（３６）と、押し子本体（３６）を前進させる前進機構（３８）と、前進機構（３８）を駆動する駆動機構（３９）と、少なくとも筒体（１２）および前進機構（３８）を支持するシャーシ部材（２４）と、筒体（１２）、押し子本体（３６）、前進機構（３８）、駆動機構（３９）およびシャーシ部材（２４）を収容するハウジング（２８）とを備える。シャーシ部材（２４）は、筒体（１２）の第１被支持部の先端面を支持する第１支持部と、前進機構（３８）の第２被支持部の基端面を支持する第２支持部とを有する。
