diff --git a/mlir/include/mlir/Dialect/EmitC/IR/EmitC.td b/mlir/include/mlir/Dialect/EmitC/IR/EmitC.td
--- a/mlir/include/mlir/Dialect/EmitC/IR/EmitC.td
+++ b/mlir/include/mlir/Dialect/EmitC/IR/EmitC.td
@@ -45,7 +45,6 @@
 
     ```
   }];
-  // TODO: Disallow to apply the operator & (address of) to emitc.constant operations.
   let arguments = (ins
     Arg<StrAttr, "the operator to apply">:$applicableOperator,
     AnyType:$operand
diff --git a/mlir/lib/Dialect/EmitC/IR/EmitC.cpp b/mlir/lib/Dialect/EmitC/IR/EmitC.cpp
--- a/mlir/lib/Dialect/EmitC/IR/EmitC.cpp
+++ b/mlir/lib/Dialect/EmitC/IR/EmitC.cpp
@@ -59,6 +59,10 @@
   if (applicableOperatorStr != "&" && applicableOperatorStr != "*")
     return emitOpError("applicable operator is illegal");
 
+  Operation *op = getOperand().getDefiningOp();
+  if (op && dyn_cast<ConstantOp>(op))
+    return emitOpError("cannot apply to constant");
+
   return success();
 }
 
diff --git a/mlir/test/Dialect/EmitC/invalid_ops.mlir b/mlir/test/Dialect/EmitC/invalid_ops.mlir
--- a/mlir/test/Dialect/EmitC/invalid_ops.mlir
+++ b/mlir/test/Dialect/EmitC/invalid_ops.mlir
@@ -80,6 +80,15 @@
 
 // -----
 
+func.func @illegal_operand() {
+    %1 = "emitc.constant"(){value = 42: i32} : () -> i32
+    // expected-error @+1 {{'emitc.apply' op cannot apply to constant}}
+    %2 = emitc.apply "&"(%1) : (i32) -> !emitc.ptr<i32>
+    return
+}
+
+// -----
+
 func.func @var_attribute_return_type_1() {
     // expected-error @+1 {{'emitc.variable' op requires attribute's type ('i64') to match op's return type ('i32')}}
     %c0 = "emitc.variable"(){value = 42: i64} : () -> i32