<p>A stirring device and a catheter whereby a thrombus can be efficiently lysed within a short period of time regardless of its size so that a blood vessel can be reopened by removing the thrombus and the extent of lysation can be determined in real time. A stirring device equipped with a tubular member, which has a discharge port for discharging a thrombolytic agent and a suction port for sucking fine matter to be lysed remaining therein, and a mechanical vibration-imparting means which is attached to the fixed end side of the tubular member and employed for disrupting the matter to be lysed and measuring at least one factor selected from among the extent of lysation of the matter to be lysed, the viscosity of the solution in which the matter to be lysed has been lysed, the hardness/viscosity of the matter to be in contact and the hardness/viscosity of an adhering matter depending on a change in impedance.</p>
