PROBLEM TO BE SOLVED: To provide a cage for a pet with high expandability, a connected cage for a pet, and a connection component set.SOLUTION: A cage for a pet includes: a tray 1 having a bottom part 11, a peripheral wall part 13 provided on a peripheral part on a side of an upper surface 11a of the bottom part 11, and a peripheral end part 15 which is the peripheral part and is provided outside the peripheral wall part 13 and a cage body 3 arranged on the peripheral end part of the tray 1. The cage body 3 has a right side surface panel 37 arranged on a first peripheral end part of the peripheral end part 15 and a rear surface panel 33 arranged on a second peripheral end part that faces in a direction different from the first peripheral end part out of the peripheral end part 15. The rear surface panel 33 is a wire panel in which a plurality of wires 331 are combined in the form of a grid. When a distance between the right side surface panel and a side surface 15c of the first peripheral end part is L1, and a distance between adjacent wires out of the plurality of the wires 331 of the rear surface panel 33 is L2, L1×2≤L2.COPYRIGHT: (C)2016,JPO&INPIT【課題】拡張性が高いペット用ケージ及びペット用連結ケージ、連結部品セットを提供する。【解決手段】底部11と、底部11の上面11a側の周辺部に設けられた周壁部13と、周辺部であって周壁部13よりも外側に設けられた周端部15とを有するトレー1と、トレー1の周端部上に配置されるケージ本体3とを備える。ケージ本体3は、周端部15のうち第1の周端部上に配置される右側面パネル37と、周端部15のうち第1の周端部とは異なる方向に面する第2の周端部上に配置される後面パネル33と、を有する。後面パネル33は複数本の線材331を格子状に組み合わせた線材パネルである。右側面パネルと第1の周端部の側面15cとの間の距離をL1とし、後面パネル33の複数本の線材331のうち隣り合う線材間の距離をL2としたとき、L1×2≦L2である。【選択図】図7