Provided are a battery module manufacturing device and a battery module manufacturing method. The battery module manufacturing device includes a cell hot pressing assembly, and the cell hot pressing assembly includes a first hot pressing part and a second hot pressing part which are oppositely disposed; the first hot pressing part includes at least one upper pressing head, and the side of each upper pressing head facing the second hot pressing part is provided with a piston inner pressing head; the second hot pressing part includes at least one lower pressing head in one-to-one correspondence to the upper pressing head, the side of each lower pressing head facing the first hot pressing part is provided with two parallel side baffles, a limiting gap is formed between the two side baffles.