A puncture assisting device includes a pair of plate-like pinching portions that face each other, and that are attached to each other so as to be openable and closeable; a biasing portion that biases the pair of pinching portions to be in a closed position; a pair of gripping portions configured to operate the pair of pinching portions to be in an open position; and a rod insertion portion that is disposed between the pair of pinching portions, the rod insertion portion being configured such that a rod portion of a syringe is insertable into the rod insertion portion to widen a gap between the pair of pinching portions.