Microchip testing device having a chip holder that can be exactly positioned and from which adhered sample liquid can be removed easily. The microchip testing device has a chip holder, with a cover and a box area, mounted on a measurement stage, a microchip that has an optical measurement chamber is housed in the chip holder, a light source that radiates light on the optical measurement chamber of the microchip, a detector that receives light that has passed through the optical measurement chamber, and a controller that controls the device. The chip holder has reference planes to position the microchip in two directions perpendicular to the optical axis of the optical measurement chamber and pushers that push the microchip against the reference planes, so that the microchip is positioned within the chip holder by closing the cover of the chip holder.