An apparatus for testing a side collision with a vehicle body connects between a side carriage for testing a side collision and a side structure which includes a roof rail part configured to be connected to an upper portion of the side carriage, a side sill part configured to be connected to a side lower part of the side carriage, and a pillar part configured to connect between the roof rail part and the side sill part and be connected to a pillar of the side carriage. The side carriage is connected to the side structure while forming a space between the side carriage and the side structure.