The present disclosure aims to provide a backdoor inspection device, a method, and a non-transitory computer-readable medium that are capable of detecting a code being highly likely to be a backdoor from software. A backdoor inspection device according to the present disclosure includes: a backdoor presuming means for analyzing a function and a structure of software and identifying a presumed code that is presumed to be a backdoor from the software; a data flow analysis means for analyzing a propagation state of confidential data in the software and identifying a confidential code that processes the confidential data; and a backdoor determination means for identifying a backdoor code that is more likely to be the backdoor than the presumed code, based on the presumed code and the confidential code.