A glass panel unit assembly includes a pair of glass substrates arranged to face each other, a peripheral wall, a partition, an air passage, and an evacuation port. The peripheral wall has a frame shape and is provided between the pair of glass substrates. The partition partitions an internal space, surrounded with the pair of glass substrates and the peripheral wall, into a first space and a second space. The air passage connects the first space and the second space together. The evacuation port connects the second space to an external environment. The partition has a broader width than the peripheral wall.