A cartridge configured to be mounted to a liquid ejection apparatus that has an electrical connection portion and an engagement portion, and having an engaging portion for engaging the engagement portion and a plurality of electrodes for connecting to the connection portion. The electrodes have contact portions for contacting the connection portion, with a first group of a plurality of the contact portions constituting a first array whose contact portions are aligned in an X-axis direction intersecting a mounting direction of the cartridge, and a second group of the plurality of the contact portions constituting a second array whose contact portions are aligned in the X-axis direction. The first and second arrays are aligned in a direction intersecting the X-axis direction, and the engaging portion and an area between the first array and the second array are aligned in the X-axis direction.