A body composition monitor for measuring a whole-body composition of a subject, comprising: a plurality of hand electrodes (E11, E12, E13, E14) and a plurality of foot electrodes (E21, E22, E23, E24); a detection portion for detecting a first potential difference between a hand and a foot by applying a current across the hand and the foot of said subject through one of each of said hand and foot electrodes, and for detecting a second potential difference between the hands by applying a current across the hands of said subject through two of said hand electrodes, or for detecting a second potential difference between the feet by applying a current across the feet of said subject through two of said foot electrodes; a first body composition calculation portion for calculating a first whole-body composition using a whole-body impedance (Zw) based on a result of detection of said first potential difference, said first body composition calculation portion calculating said first whole-body composition of said subject based on said whole-body impedance (Zw), body information of said subject, and a prescribed estimation equation showing a relation among said whole-body impedance, said body information and said whole-body composition; characterized by a correlation calculation portion for calculating a correlation between said whole-body impedance and a two-limb impedance which is obtained based on said second potential difference detected in a period of detection of said first potential difference; a storage portion for storing correlation data representing said correlation as correlation information, a correction portion for correcting said two-limb impedance (Zh, Zf) based on said correlation information, and a second body composition calculation portion for calculating a second whole-body composition using said two-limb impedance corrected by said correction portion. a plurality of hand electrodes (E11, E12, E13, E14) and a plurality of foot electrodes (E21, E22, E23, E24); a detection portion for detecting a first potential difference between a hand and a foot by applying a current across the hand and the foot of said subject through one of each of said hand and foot electrodes, and for detecting a second potential difference between the hands by applying a current across the hands of said subject through two of said hand electrodes, or for detecting a second potential difference between the feet by applying a current across the feet of said subject through two of said foot electrodes; a first body composition calculation portion for calculating a first whole-body composition using a whole-body impedance (Zw) based on a result of detection of said first potential difference, said first body composition calculation portion calculating said first whole-body composition of said subject based on said whole-body impedance (Zw), body information of said subject, and a prescribed estimation equation showing a relation among said whole-body impedance, said body information and said whole-body composition; characterized by a correlation calculation portion for calculating a correlation between said whole-body impedance and a two-limb impedance which is obtained based on said second potential difference detected in a period of detection of said first potential difference; a storage portion for storing correlation data representing said correlation as correlation information, a correction portion for correcting said two-limb impedance (Zh, Zf) based on said correlation information, and a second body composition calculation portion for calculating a second whole-body composition using said two-limb impedance corrected by said correction portion.