An image display device comprising: - a light source unit configured to output a light beam; - a scanning unit configured to reflect the light beam and repeat a reciprocating operation in a predetermined scanning direction; - a scanning detection unit configured to detect the reciprocating operation of the scanning unit and to output a signal representing the reciprocating operation in each reciprocation; - a display position determination unit configured to - determine a displacement of the image display position in each scanning line by using half of a difference between a first difference (A1-A0, C1-A0) and a second difference (B1-B0), wherein the first difference (A1-A0, C1-A0) is the difference between a count value obtained by counting a first operation range in the forward or reverse scanning line (A1, C1) as derivable from the output signal of the scanning detection unit by a counter based on an internal clock and a count value corresponding to a first reference value representing the operation range for the forward or reverse line, and wherein the second difference (B1-B0) is the difference between a count value obtained by counting the second operating range of the reciprocating operation as derivable from the output signal of the scanning detection unit by a counter based on an internal clock and a count value corresponding to a second reference value representing the operation range for the reciprocating operation; and - correct the counting start position of a pixel counter by the determined displacement of the image display position for the first operation range; - a light source driving unit configured to drive the light source unit based on image data at a timing corresponding to the value of the corrected pixel counter. - a light source unit configured to output a light beam; - a scanning unit configured to reflect the light beam and repeat a reciprocating operation in a predetermined scanning direction; - a scanning detection unit configured to detect the reciprocating operation of the scanning unit and to output a signal representing the reciprocating operation in each reciprocation; - a display position determination unit configured to - determine a displacement of the image display position in each scanning line by using half of a difference between a first difference (A1-A0, C1-A0) and a second difference (B1-B0), wherein the first difference (A1-A0, C1-A0) is the difference between a count value obtained by counting a first operation range in the forward or reverse scanning line (A1, C1) as derivable from the output signal of the scanning detection unit by a counter based on an internal clock and a count value corresponding to a first reference value representing the operation range for the forward or reverse line, and wherein the second difference (B1-B0) is the difference between a count value obtained by counting the second operating range of the reciprocating operation as derivable from the output signal of the scanning detection unit by a counter based on an internal clock and a count value corresponding to a second reference value representing the operation range for the reciprocating operation; and - correct the counting start position of a pixel counter by the determined displacement of the image display position for the first operation range; - determine a displacement of the image display position in each scanning line by using half of a difference between a first difference (A1-A0, C1-A0) and a second difference (B1-B0), wherein the first difference (A1-A0, C1-A0) is the difference between a count value obtained by counting a first operation range in the forward or reverse scanning line (A1, C1) as derivable from the output signal of the scanning detection unit by a counter based on an internal clock and a count value corresponding to a first reference value representing the operation range for the forward or reverse line, and wherein the second difference (B1-B0) is the difference between a count value obtained by counting the second operating range of the reciprocating operation as derivable from the output signal of the scanning detection unit by a counter based on an internal clock and a count value corresponding to a second reference value representing the operation range for the reciprocating operation; and - correct the counting start position of a pixel counter by the determined displacement of the image display position for the first operation range; - a light source driving unit configured to drive the light source unit based on image data at a timing corresponding to the value of the corrected pixel counter.