This paper describes a human activity monitoring system including various MEMS sensors. Currently, health care devices are in the limelight because aging of society has been progressing and it is required that we should take care our health by ourselves without the help of younger people. For health care, a continuous monitoring system for human activity is effective. The patch type devices, which are installed directly on the body, are one of the candidates for suitable human monitoring system that watches over the daily activity and physical and mental conditions. In this paper, background of the work, current status, requests to the devices and example devices will be shown as well as the example data for activity monitoring. Finally, future demands for the monitoring system are discussed.