This paper describes the research and development of an inspection diagnostic system that applies robot technology to the detailed inspection of infrastructure such as concrete walls in high places. ALP uses a vacuum suction pad improved by testing on real structures as a moving mechanism. ALP is also fitted with a measurement system that consists of a high-resolution camera, an electromagnetic wave radar, and a hammering sound diagnostic device. The result is a highly capable self-propelling inspection system that can carry out detailed inspections of infrastructure in diffi-cult-to-access locations such as high places.