A blender transmits an electrical signal via a transparent film so as to detect whether a container lid is closed. The blender includes a container body receiving food; a main body provided under the container body and supporting the container body; a container lid mounted removably to the upper surface of the container body and configured to open/close the upper part of the container body; and a detection system configured to detect whether the container lid is mounted to the container body, wherein the detection system includes a transparent electrode film attached to the surface of the container body and guiding the flow of electricity. Accordingly, the transparent electrode film can transmit whether the container lid is mounted to the main body without spoiling the appearance of the container body made of a transparent material.