To provide a rotary type agitating and mixing device which can be brought into any work site for uniformly mixing an admixture material with a material to be agitated such as sediment to be processed, in a smooth and efficient manner.

A rotary type agitating and mixing device 10 which is installed on an arm 5 of a front work machine 3 which is installed on the upper revolving superstructure 2 of a hydraulic shovel comprises agitation blade means 13 having a plurality of agitation blades 31 which is rotary driven by a hydraulic motor 11, and a storage vessel 43 which is mounted to the casing of the hydraulic motor 11 and provided with a plurality of open injection ports 44. The upper revolving superstructure 2 is provided with a storage vessel 40. An admixture liquid is supplied to the storage vessel 43 through a supply pipe 41 so as to be injected from the injection ports 44 to the internal part of an agitation region S rotated by the rotation blades 31.