Infant monitoring device and method

The invention provides an infant monitoring device. The monitoring device comprises a thermal imaging pick-up device, a controller and an alarm device, wherein the thermal imaging pick-up device and the alarm device are respectively connected with the controller through an input/output (I/O) circuit; the controller calibrates the position coordinate set of the activity range of an infant; when the infant monitoring device operates in an activity range monitoring operating mode, the controller reads thermal imaging data acquired by the thermal imaging pick-up device and calculates the positioncoordinates of the infant; and if the position coordinates are not in the position coordinate set, the alarm device is triggered to send an alarm signal to inform a guardian. The infant monitoring device can effectively monitor the activity range of the infant.