An insertion device is disclosed which is suitable for use of liquid as lubricant such as normal saline. The insertion device for inserting a lens into an eye comprises a main body having a nozzle at its front end, and a pushing member for pushing the lens set in the main body into an eye through the nozzle. The pushing member includes an introducing portion through which liquid is introduced and a flow path for supplying the liquid introduced from the introducing portion into the main body.