This invention provides a mixer without a rotational or similar structure, capable of mixing quickly several liquids including at least one liquid being prone to gel or solidify, a mixing device with the mixer incorporated, and a medical component-measuring unit capable of reducing the formation of thrombi and accurately measuring the concentration of glucose, and with a small time constant, which unit can be incorporated into medical support devices, such as artificial endocrine pancreas devices. The mixer has an air bubble-trapping structure for temporarily trapping air bubbles supplied to a surface of a mixing channel through which liquids to be mixed flow. The mixing device has the mixer, an air bubble supplier or generator to make air bubbles exist in the mixing channel, and a liquid supplier for supplying liquids to be mixed to a liquid inlet. The medical component-measuring unit has the mixer or the mixing device.
