This butterfly is seasonally variable. The upper side of the summer forms hind wings are all black, whereas the winter forms hind wings are reddish-orange. The underside of both forms is striped with dark and light brown. There is a silvery comma mark in the middle of the hindwing in both forms. Its wingspan is 4.5–6.4 cm (1.8–2.5 in) - from Wikipedia
The dark form of comma is frequently confused with the dark form of the Question Mark (N. interrogationis), but the two can readily be distinguished by the shape of the comma mark on the underside. The pale form is easily confused with the Satyr Comma (N. satyrus), which usually occurs north and west of the Eastern Comma's range. They can be distinguished by the upperside colour, which is orange brown in comma and tawny yellowish brown in satyrus; by the underside pattern, which tends to be mottled in comma but appears to be more longitudinally streaked in satyrus; and by the row of pale submarginal spots on the hindwing upperside, which tend to be separate and surrounded by dark shading in comma, but are larger and tend to run together into a pale band in satyrus. - from Wikipedia
Indeed, I was confused with Question Mark. Thanks to my website friends who helped me to identify this beautiful butterfly.