To provide a diagnostic robot system of a concrete structure for remotely diagnosing the concrete structure, and rapidly and efficiently detecting a micro defect of even a large concrete structure.

This diagnostic robot system includes a plate member fixed to the concrete structure to be diagnosed, an exciting device that is adsorbed to and separated from the plate member by remote operation and applies local vibration to the concrete structure when it is adsorbed, at least one vibration detecting means that is adsorbed to and separated from the plate member by remote operation and detects a response to the vibration of the concrete structure when it is adsorbed, a moving means for moving, by remote operation, the exciting device and at least one vibration detecting means to a position to be diagnosed in the concrete structure, and an analyzing means for determining the soundness of the concrete structure based on how the vibration mode obtained by detection of vibration detecting means varies from the vibration mode during sound time.