An applicator includes a syringe , a liquid agent injection unit provided at one end of the syringe and in communication with a liquid agent flow passage, a pusher slidably inserted from an opposite end of the syringe, a push portion at an end of the pusher opposite from a syringe side of the pusher that is inserted in the syringe and causing the liquid agent to be injected from the liquid agent injection unit by being pushed, a gas flow passage formed in a support unit supplies compressed gas to the liquid agent injection unit, and an operation unit causes a start of the supply of the compressed gas to the liquid agent injection unit. The push portion allows an operator to push the push portion with a thumb of a hand engaging the operation unit with at least one finger other than this thumb.
