The tip of an electrically conductive probe 11 is brought into contact with a sample and captures the sample S under atmospheric pressure, a high voltage for electrospray is applied to the probe 11 while a solvent is supplied to the tip of the probe 11 that has captured the sample, and molecules of the sample S at the probe tip are ionized. A miniscule amount of a fine solvent droplet is supplied to the probe tip and slow electrospray is implemented. As a result, the size of the electrically charged droplet can be made extremely small and components within the sample can be analyzed extensively without selectivity. Further, in imaging over an extended period of time, electrospray is possible even in the event that the sample dries.