According to one embodiment, target tracking device includes passive processor, active processor, fusion unit and correction unit. Passive processor calculates passive track of target based on passive measurement of target angle measured by passive sensor. Active processor calculates active track of target based on active measurement of target distance and angle measured by active sensor. Fusion unit combines passive track and active track to output combined track. Correction unit calculates correction data based on combined track. Passive processor calculates track of the target for motion models based on passive measurement and correction data and calculates passive track by weighted sum of all tracks for motion models.