Provided is a method for manufacturing a housing of a radiation detection cassette that can appropriately form a recess without a housing material depositing on an end mill or the like, in a case where a recess is formed by working the housing material formed of an alloy containing Mg and Li. A method for manufacturing a housing of a radiation detection cassette that houses a radiation detector in the housing includes preparing a housing material that is formed of an alloy containing Mg and Li and contains 0.1 mass % or more of Li, forming a recess using a working method other than cutting work on a surface of the housing material, and performing cutting work on the formed recess to shape the recess.