To provide a device capable of efficiently assembling individual products composed of two constituents and packaged.

This device is provided with a first advancing device 1 for supplying a first constituent 11 of an individual product 13. At the downstream, there is connected a second rotating advancing device 2 having a driving member 20 for a first composing element 11 and a second driving member 21 for a second composing element 1 supplied by a second supplying station 45. A third advancing device 3 rotated in a synchronous manner is provided with a pressing piston 56 which can be controlled, thereby the second composing element 12 is press-fitted into a recess 15 of the first constituent 11. This device enables a gentle handling at a high speed operation.