diff --git a/README.md b/README.md
index 4cf5aff..975f78e 100644
--- a/README.md
+++ b/README.md
@@ -658,6 +658,14 @@ For instance to run subset of tests for the first CI node with specified seed yo
 
 Above example is for RSpec. You can use respectively rake task name and token environment variable when you want to run tests for minitest, cucumber or spinach.
 
+### How can I change log level?
+
+You can change log level by specifying the `KNAPSACK_LOG_LEVEL` environment variable.
+
+    KNAPSACK_LOG_LEVEL=warn bundle exec rake knapsack:rspec
+    
+Available values are `debug`, `info`, and `warn`. The default log level is `info`.
+
 ## Gem tests
 
 ### Spec
diff --git a/lib/knapsack.rb b/lib/knapsack.rb
index 9f14943..22c920a 100644
--- a/lib/knapsack.rb
+++ b/lib/knapsack.rb
@@ -48,7 +48,7 @@ def load_tasks
     def logger
       return @@logger if @@logger
       log = Knapsack::Logger.new
-      log.level = Knapsack::Logger::INFO
+      log.level = Knapsack::Config::Env.log_level
       @@logger = log
     end
 
diff --git a/lib/knapsack/config/env.rb b/lib/knapsack/config/env.rb
index b1bd75a..3e42c7f 100644
--- a/lib/knapsack/config/env.rb
+++ b/lib/knapsack/config/env.rb
@@ -22,6 +22,14 @@ def test_dir
           ENV['KNAPSACK_TEST_DIR']
         end
 
+        def log_level
+          {
+            "debug" => Knapsack::Logger::DEBUG,
+            "info"  => Knapsack::Logger::INFO,
+            "warn"  => Knapsack::Logger::WARN,
+          }[ENV['KNAPSACK_LOG_LEVEL']] || Knapsack::Logger::INFO
+        end
+
         private
 
         def index_starting_from_one(index)
diff --git a/spec/knapsack/config/env_spec.rb b/spec/knapsack/config/env_spec.rb
index 59f4695..8115d96 100644
--- a/spec/knapsack/config/env_spec.rb
+++ b/spec/knapsack/config/env_spec.rb
@@ -110,4 +110,18 @@
       it { should be_nil }
     end
   end
+
+  describe '.log_level' do
+    subject { described_class.log_level }
+
+    context 'when ENV exists' do
+      let(:log_level) { 'debug' }
+      before { stub_const("ENV", { 'KNAPSACK_LOG_LEVEL' => log_level }) }
+      it { should eql Knapsack::Logger::DEBUG }
+    end
+
+    context "when ENV doesn't exist" do
+      it { should eql Knapsack::Logger::INFO }
+    end
+  end
 end