The present application aims to provide an automatic analysis device that improves the degree of freedom in relation to the arrangement of a dispensing mechanism or a unit provided thereunder. To this end, in an automatic analysis device provided with a dispensing mechanism that drives a probe (7a, 8a) of a
reagent or a sample, the present application is provided with: an arm (25, 30) that supports the probe (7a, 8a) in
two degrees of freedom; a first transmission shaft (26) and a second transmission shaft (40, 41) that support the arm (25, 30) and transmit power to the arm (25, 30); and a motor (28, 33, 37) that applies power that rotates and moves the first transmission shaft (26) and the second transmission shaft (40, 41) up and down, the second transmission shaft (40, 41) being split in the axial direction and having different diameters, and when the arm (25, 30) is lowered using the power of the motor (37), the second transmission shaft (40, 41) is shortened by housing one part (40) after being split inside the other part (41).