The robot simulation apparatus includes: a picking motion simulating unit 30 that verifies a picking motion from a bulk pile of workpiece models in a virtual work space, with respect to bulk pile data generated by a bulk pile data generating unit 20. A physical simulation unit 60 is configured to re-execute a physical simulation with respect to the bulk pile data of a state obtained after one workpiece model is picked up after the picking motion simulating unit 30 grasps the workpiece model and at least a picking-up motion is started. The bulk pile data generating unit 20 is configured to update bulk pile data according to the result of the physical simulation executed by the physical simulation unit 60 during the simulation of the picking motion by the picking motion simulating unit 30.