PURPOSE: To provide a compact, low-cost particulate measuring device capable of adequately accommodating for variation in ambient temperature in between switching points of a branch line, and large load variation.

CONSTITUTION: A plurality of branch lines 5, 6 introduced from a dilution tunnel 1 are joined in one line, connected to a single sampling line 11 at a junction B, and a flow rate control valve 15, a suction pump 17, a flow rate sensor 18 are arranged in order in the downstream position from the junction B in the sampling line 11, and a temperature sensor 19 is installed at least in the flow rate sensor 18 or in its vicinity. A controller 20 for controlling the valve opening of the flow rate control valve 15 based on the valve opening of the flow rate control valve 15 in switching in the preceding time of the branch lines 5, 6, and flow rate information from the flow rate sensor 18 after switching and temperature information from the temperature sensor 19 so that the flow rate of the exhaust gas becomes constant before and after the switching is installed.