Provided are a projection type display device and a projection control method capable of accurately performing information presentation to an operator of a vehicle even in an image light shielded state where image light to be projected onto a projection surface is shielded by an object. An HUD 10 that is mounted in a construction machine 100 having a windshield 5 notifies, in a case where it is detected that image light to be projected onto the windshield 5 is in an image light shielded state where at least a part of the image light is shielded by an object, such as part of the body of an operator of a vehicle, the presence of the state.