A portable medicinal-liquid administering device for continuously or intermittently administering medicinal liquid filling a medicinal liquid storage into a living body by pressing, toward the medicinal liquid, a pressing member to be operated by driving force from a driving source, the medicinal-liquid administering device comprising: a reusable part that is reusable; and a disposable part that is provided to be attachable/detachable to/from the reusable part and is disposable, wherein the reusable part includes: the driving source; a reusable-side power transmission part to which the driving force from the driving source is transmitted; a housing that houses the reusable-side power transmission part and is provided with an opening part partially exposing the reusable-side power transmission part; an openable/closable cover part provided at the opening part of the housing; and a pushing member that pushes the cover part into a closed state, the disposable part includes: the medicinal liquid storage; the pressing member; a disposable-side power transmission part that engages with the reusable-side power transmission part upon attachment of the reusable part and the disposable part and transmits, to the pressing member, the driving force transmitted from the driving source to the reusable-side power transmission part; and characterized in that it further comprises a contact part capable of contacting the cover part, and the contact part contacts the cover part in order to open it and maintain it in an open state while resisting pushing force of the pushing member when the disposable part is attached to the reusable part, and the cover part is closed to block the opening part by the pushing force of the pushing member when the disposable part is detached from the reusable part, and wherein the cover part is rotatably mounted on the housing via a shaft, and the pushing member pushes the cover part into the closed state by applying the pushing force to the cover part along a circumferential direction of the shaft, and the reusable-side power transmission part includes an output gear is driven or rotated by the driving force from the driving source, the output gear is partially exposed outside of the housing via the opening part when the cover part is in the opened state, and the disposable-side power transmission part includes an input gear capable of meshing with the output gear. a reusable part that is reusable; and a disposable part that is provided to be attachable/detachable to/from the reusable part and is disposable, wherein the reusable part includes: the driving source; a reusable-side power transmission part to which the driving force from the driving source is transmitted; a housing that houses the reusable-side power transmission part and is provided with an opening part partially exposing the reusable-side power transmission part; an openable/closable cover part provided at the opening part of the housing; and a pushing member that pushes the cover part into a closed state, the driving source; a reusable-side power transmission part to which the driving force from the driving source is transmitted; a housing that houses the reusable-side power transmission part and is provided with an opening part partially exposing the reusable-side power transmission part; an openable/closable cover part provided at the opening part of the housing; and a pushing member that pushes the cover part into a closed state, the disposable part includes: the medicinal liquid storage; the pressing member; a disposable-side power transmission part that engages with the reusable-side power transmission part upon attachment of the reusable part and the disposable part and transmits, to the pressing member, the driving force transmitted from the driving source to the reusable-side power transmission part; and characterized in that it further comprises a contact part capable of contacting the cover part, and the medicinal liquid storage; the pressing member; a disposable-side power transmission part that engages with the reusable-side power transmission part upon attachment of the reusable part and the disposable part and transmits, to the pressing member, the driving force transmitted from the driving source to the reusable-side power transmission part; and characterized in that it further comprises a contact part capable of contacting the cover part, and the contact part contacts the cover part in order to open it and maintain it in an open state while resisting pushing force of the pushing member when the disposable part is attached to the reusable part, and the cover part is closed to block the opening part by the pushing force of the pushing member when the disposable part is detached from the reusable part, and wherein the cover part is rotatably mounted on the housing via a shaft, and the pushing member pushes the cover part into the closed state by applying the pushing force to the cover part along a circumferential direction of the shaft, and the reusable-side power transmission part includes an output gear is driven or rotated by the driving force from the driving source, the output gear is partially exposed outside of the housing via the opening part when the cover part is in the opened state, and the disposable-side power transmission part includes an input gear capable of meshing with the output gear.