A biological monitoring device for accurately detecting a sudden abnormality of a living organism is provided. A biological information measurement unit (33) measures biological information of patient P for each predetermined measurement cycle by vital sensors (10)(11), and stores in a memory (32). A dispersion degree calculation unit (34) calculates dispersion degree of the biological information in a predetermined measurement period Tw, referring to time series data of the biological information stored in the memory (32). A divergence degree calculation unit (35) calculates, for evaluation biological information which is the biological information measured at a predetermined point after measurement period Tw, a divergence degree of the evaluation biological information from a dispersion range of the biological information in measurement period Tw, based on the dispersion degree. An abnormality determination unit (36) determines that patient P is in abnormal state, when the divergence degree is a predetermined level or more.
