An absolute displacement detection device adapted to calculate, from a plurality of displacement detection signals (Ss, Sp, Sq) detected by a plurality of displacement detection mechanisms (12a, 12b, 13a, 14a, 15a-c) that detect displacement amounts, an absolute periodic signal (g) that indicates an absolute displacement amount, having a period larger than periods of a plurality of the displacement detection signals, the absolute displacement detection device comprising: first computation means that generates, from a plurality of the displacement detection signals, a first periodic signal (p) and a second periodic signal (q) which are different in period, the first periodic signal and the second periodic signal being digitized with a common base unit amount (u) and the second periodic signal being changed in synchronization with a change of the first periodic signal; second computation means that calculates a first remainder (d) by dividing a difference (c), between a value resulting from multiplying the first periodic signal by a first coefficient and a value resulting from multiplying the second periodic signal by a second coefficient, by a common multiple of a period of the first periodic signal and a period of the second periodic signal, the first coefficient being a value resulting from dividing the common multiple by the period of the first periodic signal, and the second coefficient being a value resulting from dividing the common multiple by the period of the second periodic signal; third computation means that calculates a second remainder (e) by dividing the first remainder by a difference between the first coefficient and the second coefficient; and fourth computation means that calculates the absolute periodic signal (g) by adding to the first remainder a value (f) resulting from multiplying the second remainder by the common multiple. first computation means that generates, from a plurality of the displacement detection signals, a first periodic signal (p) and a second periodic signal (q) which are different in period, the first periodic signal and the second periodic signal being digitized with a common base unit amount (u) and the second periodic signal being changed in synchronization with a change of the first periodic signal; second computation means that calculates a first remainder (d) by dividing a difference (c), between a value resulting from multiplying the first periodic signal by a first coefficient and a value resulting from multiplying the second periodic signal by a second coefficient, by a common multiple of a period of the first periodic signal and a period of the second periodic signal, the first coefficient being a value resulting from dividing the common multiple by the period of the first periodic signal, and the second coefficient being a value resulting from dividing the common multiple by the period of the second periodic signal; third computation means that calculates a second remainder (e) by dividing the first remainder by a difference between the first coefficient and the second coefficient; and fourth computation means that calculates the absolute periodic signal (g) by adding to the first remainder a value (f) resulting from multiplying the second remainder by the common multiple.