To provide a device for manufacturing a fabricated concrete product which requires no troublesome operation, is capable of especially removing surface air bubbles from the fabricated concrete product, and consequently does not impart a load to environments, and to provide a method for manufactur ing said product.

This device has a first airtight chamber 10 with a receiving space 11 in which a frame M for the fabricated concrete product can be freely arranged; a second airtight chamber 20 which is airtightly connected with the first airtight chamber 10, has storage spaces 22a and 22b for storing a ready- mixed concrete RC, and enables the storage space 22a and 22b to freely communicate with the receiving space 11 of the first airtight chamber 10 through openings 23a and 23b; and a vacuum pump 41 as an atmospheric pressure change means which at least realizes a pressure reduction function to create a vacuum state, by reducing the internal pressure of the first airtight chamber 10 and the second airtight chamber 20.