The present invention provides a liquid sample suctioning device capable of simplifying a structure thereof, preventing clogging of a pipette and contamination of a liquid sample, and closing a hole formed in a lid after the liquid sample is suctioned. The liquid sample suctioning device is adapted to suction the liquid sample in the container by piercing through the lid mounted on an opening of the container, comprising a piercer having a leading end insertable into the container by piercing through the lid and forming a deformation piece deformable toward an inner side of the container in the lid, a pipette configured for suctioning the liquid sample in the container, a first driving part for moving up and down the piercer, and a second driving part for moving up and down the pipette along the piercer.