A scanning endoscope system comprising: a fiber configured to guide illuminating light emitted from a light source; a light collection optical system configured to collect the illuminating light entered through the fiber to make the illuminating light exit toward an object; an optical scanning section configured to include two pairs of piezoelectric elements (15a, 15b, 15c, 15d) disposed at positions facing each other across the fiber, the optical scanning section being configured to drive the two or more pairs of piezoelectric elements (15a, 15b, 15c, 15d) to allow swinging the fiber such that positions in the object illuminated by the illuminating light from the light collection optical system form a trajectory according to a predetermined scanning pattern; a drive signal output section configured to output a first drive signal having a waveform with a positive voltage value at the center to a first piezoelectric element (15a, 15c) of a first pair of piezoelectric elements disposed along a first axis direction, which is a direction across the fiber, in the optical scanning section, the first piezoelectric element (15a, 15c) having a polarization direction which agrees with the first axis direction and the first piezoelectric element (15a, 15c) expanding and contracting along a second axis direction which is a direction along the fiber, and to output a second drive signal having a waveform with a negative voltage value at the center, and having a same phase as a phase of the first drive signal to a second piezoelectric element (15b, 15d) of the first pair of piezoelectric elements, the second piezoelectric element (15b, 15d) having a same polarization direction as the polarization direction of the first piezoelectric element (15a, 15c) and expanding and contracting in a direction opposite to the second axis direction; an input section configured to allow provision of an instruction to individually change the positive voltage value and the negative voltage value; a memory (16, 24) configured to store set values for the positive voltage value and the negative voltage value changed according to the instruction provided via the input section for correcting a misalignment between an optical axis of the light collection optical system and a position at a center of the trajectory of the positions illuminated by the illuminating light formed according to the predetermined scanning pattern; and a controller configured to perform control to change at least one of the positive voltage value and the negative voltage value, based on the set values read from the memory (16, 24). a fiber configured to guide illuminating light emitted from a light source; a light collection optical system configured to collect the illuminating light entered through the fiber to make the illuminating light exit toward an object; an optical scanning section configured to include two pairs of piezoelectric elements (15a, 15b, 15c, 15d) disposed at positions facing each other across the fiber, the optical scanning section being configured to drive the two or more pairs of piezoelectric elements (15a, 15b, 15c, 15d) to allow swinging the fiber such that positions in the object illuminated by the illuminating light from the light collection optical system form a trajectory according to a predetermined scanning pattern; a drive signal output section configured to output a first drive signal having a waveform with a positive voltage value at the center to a first piezoelectric element (15a, 15c) of a first pair of piezoelectric elements disposed along a first axis direction, which is a direction across the fiber, in the optical scanning section, the first piezoelectric element (15a, 15c) having a polarization direction which agrees with the first axis direction and the first piezoelectric element (15a, 15c) expanding and contracting along a second axis direction which is a direction along the fiber, and to output a second drive signal having a waveform with a negative voltage value at the center, and having a same phase as a phase of the first drive signal to a second piezoelectric element (15b, 15d) of the first pair of piezoelectric elements, the second piezoelectric element (15b, 15d) having a same polarization direction as the polarization direction of the first piezoelectric element (15a, 15c) and expanding and contracting in a direction opposite to the second axis direction; an input section configured to allow provision of an instruction to individually change the positive voltage value and the negative voltage value; a memory (16, 24) configured to store set values for the positive voltage value and the negative voltage value changed according to the instruction provided via the input section for correcting a misalignment between an optical axis of the light collection optical system and a position at a center of the trajectory of the positions illuminated by the illuminating light formed according to the predetermined scanning pattern; and a controller configured to perform control to change at least one of the positive voltage value and the negative voltage value, based on the set values read from the memory (16, 24).