Blood pressure measurement apparatus and blood pressure measurement method

A blood pressure measurement apparatus includes a blood pressure measurement unit, a bio-information acquisition unit, a depth calculation unit, a storage unit and a decision unit. The bio-information acquisition unit continuously acquires bio-information of a subject. The depth calculation unit repeatedly calculates depth indices each indicating a sleep stage of the subject on the basis of the acquired bio-information. The storage unit stores the calculated depth indices. The decision unit decides whether the sleep stage of the subject in sleep satisfies a starting condition, on the basis of a first depth index stored in the storage unit and a second depth index calculated by the depth calculation unit. The blood pressure measurement unit measures blood pressure data of the subject when the sleep stage is decided to satisfy the starting condition.