To provide a case of a noise absorbing device, which is small in diameter and size and has a large mechanical strength.

A first connector 11, a first core housing part 10 and a second connector 12 are successively set in a first case member 1. Side walls partitioning the first connector 11, first core housing part 10 and second connector 12 are large in thickness in the first and second connectors 11 and 12 and are small in thickness in the first core housing part 10. A third connector 31, a second core housing part 30 and a fourth connection part 32 are successively set in a second case member 1. Side walls partitioning the third connector 31, second core housing part 30 and fourth connector 32 are large in thickness in the third and fourth connectors 31 and 32 and are small in thickness in the second core housing part 30. The first and second case members 1 and 2 are connected with each other by the first to fourth connectors 11 to 32.