Provided are a detection device, a communications terminal, and a state collection system that enable an operator to recognize an operation result even in a noisy environment. A detection device 10 includes: a tag unit 18 to which information can be written contactlessly; a light-emitting body 15 that is capable of being lit in a predetermined pattern; and a control unit 11. The control unit 11 determines whether information that has been written to the tag unit 18 is normal and, upon determining that the information is normal, lights the light-emitting body 15 in a first pattern.