An entrapment prevention and detection device for an opening/closing mechanism detects entrapment with a simple structure and does not occupy much space. When a foreign object, such as a human body part approaches a window glass, such as an automobile window, the capacitance of a capacitive sensor increases. A control circuit compares a most recent capacitance obtained by a capacitance detection circuit with a previous value and if the most recent capacitance value is greater than the previous value, when the glass is being raised (closed), the control circuit determines that a foreign object has approached the glass and then stops or lowers (opens) the glass.