The invention provides a needle moving device which can detect a fault in a signal provided by a system controller to a performing device. An X-direction driving motor (4a) and a Y-direction driving motor (4b) in a driving portion (4) of an autosampler (1a) are provided with encoders (12a, 12b) for measuring moving distances of a needle (2) in respective directions from rotation numbers of the respective driving motors (4a and 4b). A determining portion (20) provided to a system controller (1b) locates a position of the needle (2) after the movement based on signals from the encoders (12a, 12b) and determines whether the position is a position of a designated sample vessel.