Recently, the market for masks has been growing due to air pollution, sun protection, pollen allergies and other reasons. In addition, the demand for masks has increased dramatically due to the new coronavirus from 2020, and masks are still one of the necessities of life. Although the reliance on masks is increasing, there are many inconveniences associated with wearing masks for long periods of time. At the same time, technology is developing rapidly, and the demand for smart wearable devices is increasing. Therefore, at the moment when the fourth industrial revolution is underway, combining people's common necessities with IoT technology to bring new convenient experiences to people is an important direction for future technology development and product development. In this study, smart masks were designed and implemented using IoT(Internet of Things) technology. The mask uses a microcomputer Adafruit circuit playground express, using the microcomputer's LED, optical sensors, can be in the dark place light, and through the temperature sensor real-time grasp of body temperature changes. If the body temperature rises above normal, the LED will turn "on" and activate the voice sensor to warn yourself and others around you.