Who is in charge of the Canadian federal government?

Her Majesty the Queen of Canada is the Canadian head of State (represented as of 27 September 2005 by Her Excellency the Right Honourable Michaëlle Jean, Governor General of Canada), and the Right Honourable Stephen Harper, prime minister, is the head of Government. Most of the Queen's functions are exercised only on the advice of the prime minister and ministers, meaning that the weight of decision-making power rests with the prime minister.