TypeError: a bytes-like object is required, not 'str'

[minji-o-j]

import csv

with open('mycsvfile.csv','wb') as f:
    w = csv.writer(f)
    w.writerow(list_dict.keys())
    w.writerow(list_dict.values())

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-28-325365e4f33b> in <module>()
      3 with open('mycsvfile.csv','wb') as f:
      4     w = csv.writer(f)
----> 5     w.writerow(list_dict.keys())
      6     w.writerow(list_dict.values())

TypeError: a bytes-like object is required, not 'str'