A scanner comprising at least one laser stimulating ray source for emitting a laser beam, a sample stage on which a sample carrier for carrying at least one sample is to be placed, a scanning means for moving the sample stage in a main scanning direction and in a sub-scanning direction, a confocal optical system, a drive means for an objective lens incorporated in the confocal optical system, a light detector for photoelectrically detecting light, a non-volatile memory, and a control means, the non-volatile memory being constituted so as to store position data produced by setting at least one distance measuring device in the sample carrier for carrying at least one sample, placing the sample carrier on the sample stage, and measuring a distance between the objective lens incorporated in the confocal optical system and a reference position on a surface of the at least one distance measuring device set in the sample carrier and a distance between the objective lens and at least one of the measurement positions on a surface of the at least one distance measuring device different from the reference position, and to store focus position data produced by setting a focus position determination device including a luminescent material having a property to release fluorescence emission or photoluminescence emission upon being irradiated with the laser beam in the sample carrier so that the luminescent material is located at the reference position, scanning the focus position determination device with the laser beam to stimulate the luminescent material located at the reference position, photoelectrically detecting fluorescence emission or photoluminescence emission released from the luminescent material by the light detector, changing the position of the objective lens of the confocal optical system with a predetermined pitch, and determining a focus position of the confocal optical system, the control means being constituted so as to correct the focus position data of the confocal optical system stored in the non-volatile memory with the position data stored in the non-volatile memory, and output a drive signal to the drive means based on the thus corrected focus position data of the confocal optical system, thereby causing it to move the objective lens of the confocal optical system and adjust the position of the objective lens.