An activity state analysis device comprising: a measurement unit configured to be attached to a measurement target person and configured to measure an acceleration; a tilt calculation unit configured to obtain an angle of a tilt of an upper part of a body of the measurement target person based on the acceleration measured by the measurement unit; a posture determination unit configured to determine a posture of the measurement target person based on the angle of the tilt obtained by the tilt calculation unit; a body motion calculation unit configured to obtain a magnitude of a body motion of the measurement target person based on the acceleration measured by the measurement unit; characterized by an activity state determination unit configured to determine, based on the posture determined by the posture determination unit and the magnitude of the body motion calculated by the body motion calculation unit, whether an activity state of the measurement target person is a first state or a second state different from the first state; an activity state correction unit configured to, if, in a time series of the activity state obtained by the activity state determination unit, the activity state transitions from one state of the first state and the second state to the other state, and the other state continues for a predetermined time defined in advance, determine that the activity state has transitioned from the one state to the other state, and if the other state does not continue for the predetermined time, determine that the activity state has not transitioned from the one state to the other state; and a time correction unit configured to, when the activity state correction unit determines that the activity state has transitioned from the one state to the other state, set a time set back by the predetermined time from a time at which the activity state correction unit determines that the activity state has transitioned from the one state to the other state, as a transition time at which the activity state has transitioned from the one state to the other state. a measurement unit configured to be attached to a measurement target person and configured to measure an acceleration; a tilt calculation unit configured to obtain an angle of a tilt of an upper part of a body of the measurement target person based on the acceleration measured by the measurement unit; a posture determination unit configured to determine a posture of the measurement target person based on the angle of the tilt obtained by the tilt calculation unit; a body motion calculation unit configured to obtain a magnitude of a body motion of the measurement target person based on the acceleration measured by the measurement unit; characterized by an activity state determination unit configured to determine, based on the posture determined by the posture determination unit and the magnitude of the body motion calculated by the body motion calculation unit, whether an activity state of the measurement target person is a first state or a second state different from the first state; an activity state correction unit configured to, if, in a time series of the activity state obtained by the activity state determination unit, the activity state transitions from one state of the first state and the second state to the other state, and the other state continues for a predetermined time defined in advance, determine that the activity state has transitioned from the one state to the other state, and if the other state does not continue for the predetermined time, determine that the activity state has not transitioned from the one state to the other state; and a time correction unit configured to, when the activity state correction unit determines that the activity state has transitioned from the one state to the other state, set a time set back by the predetermined time from a time at which the activity state correction unit determines that the activity state has transitioned from the one state to the other state, as a transition time at which the activity state has transitioned from the one state to the other state.