A liquid dispensing apparatus that is adapted to eject a liquid in a measuring bore by moving a piston reciprocally, the liquid dispensing apparatus comprising: a liquid contact member that has first and second measuring bores ; a first piston sliding in the first measuring bore in close contact therewith and a second piston sliding in the second measuring bore in close contact therewith; a supply channel communicating with a storage unit ; an ejection channel communicating with a nozzle ; a switching valve that is disposed in a space in the liquid contact member , and that has a first position at which the first measuring bore is communicated with the supply channel and the second measuring bore is communicated with the ejection channel , and a second position at which the first measuring bore is communicated with the ejection channel and the second measuring bore is communicated with the supply channel ; and a valve driving mechanism that is adapted to operate the switching valve; wherein the liquid dispensing apparatus is adapted to suck the liquid into the first and second measuring bores and eject the liquid in the first and second measuring bores , and comprises a piston driving mechanism that is adapted to operate an arm connected to the first and second pistons , wherein the first and second measuring bores are arranged to oppose to each other on both sides of the switching valve , and the supply channel and the ejection channel are arranged adjacent to the switching valve , characterized in that the valve driving mechanism and the piston driving mechanism are disposed at rear side of the liquid contact member adjacent to each other in a vertical direction. a liquid contact member that has first and second measuring bores ; a first piston sliding in the first measuring bore in close contact therewith and a second piston sliding in the second measuring bore in close contact therewith; a supply channel communicating with a storage unit ; an ejection channel communicating with a nozzle ; a switching valve that is disposed in a space in the liquid contact member , and that has a first position at which the first measuring bore is communicated with the supply channel and the second measuring bore is communicated with the ejection channel , and a second position at which the first measuring bore is communicated with the ejection channel and the second measuring bore is communicated with the supply channel ; and a valve driving mechanism that is adapted to operate the switching valve; wherein the liquid dispensing apparatus is adapted to suck the liquid into the first and second measuring bores and eject the liquid in the first and second measuring bores , and comprises a piston driving mechanism that is adapted to operate an arm connected to the first and second pistons , wherein the first and second measuring bores are arranged to oppose to each other on both sides of the switching valve , and the supply channel and the ejection channel are arranged adjacent to the switching valve , characterized in that the valve driving mechanism and the piston driving mechanism are disposed at rear side of the liquid contact member adjacent to each other in a vertical direction. <EOS>