service.kt interface FileUploadService { @Multipart @PUT("/admin/upload/signature") fun upload( @Part file: MultipartBody.Part, @Part(value = "num") num : RequestBody, @Part(value = "user_num") user_num : RequestBody ) : Call } MainActivity.kt var fileBody = RequestBody.create(MediaType.parse("image/png"),file); var filePart = MultipartBody.Part.createFormData("file", file?.name, fileBody); var ..