diff --git a/Lib9c.GraphQL/Types/BigIntegerType.cs b/Lib9c.GraphQL/Types/BigIntegerType.cs
new file mode 100644
index 00000000..addbe847
--- /dev/null
+++ b/Lib9c.GraphQL/Types/BigIntegerType.cs
@@ -0,0 +1,62 @@
+using System.Numerics;
+using HotChocolate;
+using HotChocolate.Language;
+using HotChocolate.Types;
+using System.Globalization;
+
+namespace Lib9c.GraphQL.Types;
+
+public class BigIntegerType : ScalarType<BigInteger, StringValueNode>
+{
+    public BigIntegerType() : base("BigInteger")
+    {
+    }
+
+    public override IValueNode ParseResult(object? resultValue)
+    {
+        return resultValue switch
+        {
+            BigInteger bigInteger => ParseValue(bigInteger),
+            string s => ParseValue(s),
+            _ => throw new SerializationException(
+                ErrorBuilder.New()
+                    .SetMessage("Invalid runtime type. Expected: BigInteger or string.")
+                    .SetCode(ErrorCodes.Scalars.InvalidRuntimeType)
+                    .Build(),
+                this)
+        };
+    }
+
+    protected override BigInteger ParseLiteral(StringValueNode valueSyntax) =>
+        BigInteger.Parse(valueSyntax.Value, CultureInfo.InvariantCulture);
+
+    protected override StringValueNode ParseValue(BigInteger runtimeValue) =>
+        new(runtimeValue.ToString(CultureInfo.InvariantCulture));
+
+    public override bool TrySerialize(object? runtimeValue, out object? resultValue)
+    {
+        if (runtimeValue is BigInteger bigInteger)
+        {
+            resultValue = bigInteger.ToString(CultureInfo.InvariantCulture);
+            return true;
+        }
+
+        resultValue = null;
+        return false;
+    }
+
+    public override bool TryDeserialize(object? resultValue, out object? runtimeValue)
+    {
+        if (resultValue is string s)
+        {
+            if (BigInteger.TryParse(s, NumberStyles.Any, CultureInfo.InvariantCulture, out BigInteger bigInteger))
+            {
+                runtimeValue = bigInteger;
+                return true;
+            }
+        }
+
+        runtimeValue = null;
+        return false;
+    }
+}
diff --git a/Mimir/Program.cs b/Mimir/Program.cs
index 7502f54e..38d51c7c 100644
--- a/Mimir/Program.cs
+++ b/Mimir/Program.cs
@@ -57,6 +57,7 @@
     .AddLib9cGraphQLTypes()
     .AddMimirGraphQLTypes()
     .BindRuntimeType(typeof(Address), typeof(AddressType))
+    .BindRuntimeType(typeof(BigIntegerType), typeof(BigIntegerType))
     .BindRuntimeType(typeof(HashDigest<SHA256>), typeof(HashDigestSHA256Type))
     .AddErrorFilter<ErrorFilter>()
     .ModifyRequestOptions(requestExecutorOptions => { requestExecutorOptions.IncludeExceptionDetails = true; });