To provide a test container sealing device which allows a sealing operation to be performed more efficiently than before.

This device includes a test container sealing mechanism 3 which seals the mouth of a test container 1 with a film 2, a test container stand supply mechanism 5 by which test container stands 4 on which a plurality of test containers 1 are placed upright are sequentially supplied to the sealing mechanism 3, and a film stretching mechanism 6 by which the film 2 is stretched at a position corresponding to the mouth of each of the plurality of test containers 1 supplied to the test container sealing mechanism 3. The plurality of test containers 1 placed upright on the test container stands 4 are sealed while being arranged along the film 2 stretched.