To provide a poppet valve type flow measuring device with simple constitution, easy to work, and capable of accurately detecting a flow rate.

This device has a poppet valve 10 for communicating with or shutting out an inflow port and an outflow part by being inserted into a body causing 1 forming the inflow port 2 and the outflow port 3 coaxially as the inflow port, and movably so as to contact with or separate from a valve seat 4 installed between the inflow port and the outflow port. The device also has a spring 11 energizing the poppet valve in the valve closing direction; a pressure receiving part 14 energizing the poppet valve in the valve closing direction by the pressure of pressure oil of the outflow port; and a projecting restriction part 12 projecting from a valve body part 10a contacting with or separating from the valve seat to a position upstream than the inflow port, and also functioning as a pressure receiving part energizing the poppet valve in the valve opening direction by the pressure of pressure fluid of the inflow port. The outer surface of the restriction part is formed by connecting plural tapered concentric conical slopes gradually forming an acute angle toward the tip of the restriction part.