The Devil's Machine is a massive device that appears in EarthBound, and serves to contain Giygas and his tremendous power and stabilize his mind. During the end of the game, Ness and company enter a hole in the Cave of the Past, which leads to a room composed of several pulsing "flesh" tubes; the tubes converge at the end of the "room" where the machine's 'core' (and Giygas) reside. Approaching him causes Ness's face to appear on the machine, and Pokey Minch appears in his spider mech, taunting the party before beginning the final boss battle.
During the battle, the Devil's Machine effectively makes Giygas invincible, as it counters any attack that hits him and deals double damage to the attacking party member(s). Once Pokey's HP is depleted, he decides to shut the device off, unleashing Giygas' power and destroying it. The result is a chaotic, bizarre dimension that traps Pokey and the four children in darkness until Paula's prayers eventually defeat Giygas.
Giygas cannot be harmed in any way due to his shield, which automatically reflects all attacks and cannot be removed. The only way to progress past this phase is to lower Pokey's HP. At the beginning of the battle, have Paula put up a PSI Shield Σ to stop Giygas' PK Rockin attack. It is very important not to put up reflective shields (β, Ω), since Giygas's own reflective shield will cause the attack to hit you.
Direct all attacks to Pokey. Ness should use Paralysis in order to cripple Pokey's offenses, and then Bash. Paula and Poo should use the highest forms of PK Freeze available. Jeff should use any Multi Bottle Rockets available to him, or simply Shoot.
- Giygas' form while in the Devil's Machine may be a reference to Sosai X, the main antagonist and leader of Galactor of Science Ninja Team Gatchaman.
- If Giygas was defeated and the Debug Menu is used to enter Giygas's Lair, it will be possible to fight him again as if the game weren't completed yet.
- If the game detects that it has been pirated, the final part of EarthBound's copy protection will kick in at the end of the battle with Pokey. Once Pokey turns off the Devil's Machine, the game will softlock, with the save file being erased upon restarting EarthBound.
- Judging by the floors in the chamber, the "Devil's Machine" almost looks likes a woman's uterus or cervix.