An automatic analyzer which can perform automatic re-measurement, can release a sample for transfer to another unit, can easily perform pre-dilution of the sample, and is adaptable for a reduction in amount of the sample. The automatic analyzer comprises a reaction disk holding a plurality of reaction cells arranged in a row along the circumference of the reaction disk, and a sample dispensing mechanism for dispensing samples into the reaction cells on the reaction disk. The sample dispensing mechanism comprises a dispensing nozzle for dispensing the samples and a support mechanism for supporting the dispensing nozzle, and the support mechanism is disposed inside the circumference of the reaction disk along which the reaction cells are arranged in a row.