A wearable electrocardiogram (ECG) monitor is evaluated as heart rate variability (HRV) monitor. The device consists of an armband designed to be worn on the left upper arm which provides 3 ECG channels based on 3 pairs of dry (no hydrogel) electrodes. Armband-ECG and conventional-Holter-ECG signals were simultaneously recorded from 14 subjects during 5 minutes in supine position. Spacial principal component analysis was used to obtain a unique armband ECG signal in which the electromyogram contribution is attenuated. QRS complexes were automatically detected. Five traditional HRV parameters were derived: SDNN, RMSSD, pNN50, and powers within low frequency (LF, [0.04, 0.15] Hz) and high frequency (HF, [0.15, 0.4] Hz) bands. The Pearson's correlation coefficient between the measurements from the armband device and the measures from the Holter device was computed. Results show very high correlations (1.0000, 0.9999, 0.9984, 1.0000, and 0.9999 for SDNN, RMSSD, pNN50, and powers at LF and HF, respectively), suggesting that the quality of armband-ECG signals is enough to estimate HRV parameters during stationary movement restricted conditions.