Disclosed is a prophylactic and/or ameliorating agent for insulin resistance, particularly a prophylactic and/or ameliorating agent for insulin resistance which can prevent and/or ameliorate insulin resistance induced by high-fat foods or feeds. Specifically disclosed is a prophylactic and/or ameliorating agent for insulin resistance which comprises a,a-trehalose as an active ingredient, particularly a prophylactic and/or ameliorating agent for insulin resistance which comprises a,a-trehalose as an active ingredient and can prevent and/or ameliorate insulin resistance induced by high-fat foods or feeds.