Provided are a monitoring device and method. A monitoring device includes a laser processor configured to emit a processing laser beam to perform a melting annealing process on a wafer; a laser monitor configured to emit a monitoring laser beam onto the wafer while the laser processor performs the melting annealing process, the laser monitor configured to measure reflectivity of the wafer; and a data processor configured to process data on the reflectivity measured by the laser monitor, and monitor one or more characteristics of the wafer based on the data on the reflectivity.