A liquid medicine filling device includes a container mounting unit, a liquid delivery flow conduit, a ventilation flow conduit, a syringe, a connection flow conduit, a first flow path switching unit, and a second flow path switching unit. The first flow path switching unit may switch between a flow path for filling through which the syringe communicates with a liquid medicine container via the ventilation flow conduit and a flow path for air removal through which the syringe communicates with the connection flow conduit via the ventilation flow conduit. The second flow path switching unit may switch between a flow path for filling through which the liquid medicine container communicates with the liquid medicine storage unit via the liquid delivery flow conduit and a flow path for air removal through which the liquid medicine storage unit communicates with the connection flow conduit via the liquid delivery flow conduit.