An all-in-one computer including a main body and an electronic assembly is provided. The main body includes a first casing part and a second casing part. The second casing part is movably connected to the first casing part and configured to move between a first position and a second position in relative to the first casing part, and the first casing part has an engaging portion and an electrical connection portion. The electronic assembly is disposed in the second casing part. When the second casing part is located at the first position, the second casing part is engaged with the engaging portion and the electronic assembly is connected to the electrical connection portion, and when the second casing part is located at the second position, the second casing part is departed from the engaging portion and the electronic assembly is departed from the electrical connection portion.