There is provided an automatic analysis device with a structure in which a measurement unit is less susceptible to disturbance as compared to a device in the related art, and a method of designing the automatic analysis device. A first rotation axis 301 of a reaction disk 1, a second rotation axis 302 of a reagent disk 9, and a measurement unit are arranged on the same straight line 311 when an automatic analysis device 100 is viewed from an upper surface side, the first rotation axis 301 of the reaction disk 1 is arranged between the second rotation axis 302 of the reagent disk 9 and the measurement unit, and the measurement unit is arranged on a front side to be accessed by a user of the automatic analysis device 100.