diff --git a/cpp/src/parquet/encoding.cc b/cpp/src/parquet/encoding.cc
index 9ab792d7e50d8..9c95eb74d3c0b 100644
--- a/cpp/src/parquet/encoding.cc
+++ b/cpp/src/parquet/encoding.cc
@@ -2414,11 +2414,7 @@ class DeltaBitPackDecoder : public DecoderImpl, virtual public TypedDecoder<DTyp
   void SetData(int num_values, const uint8_t* data, int len) override {
     // num_values is equal to page's num_values, including null values in this page
     this->num_values_ = num_values;
-    if (decoder_ == nullptr) {
-      decoder_ = std::make_shared<::arrow::bit_util::BitReader>(data, len);
-    } else {
-      decoder_->Reset(data, len);
-    }
+    decoder_ = std::make_shared<::arrow::bit_util::BitReader>(data, len);
     InitHeader();
   }
 
@@ -2777,11 +2773,7 @@ class DeltaLengthByteArrayDecoder : public DecoderImpl,
 
   void SetData(int num_values, const uint8_t* data, int len) override {
     DecoderImpl::SetData(num_values, data, len);
-    if (decoder_ == nullptr) {
-      decoder_ = std::make_shared<::arrow::bit_util::BitReader>(data, len);
-    } else {
-      decoder_->Reset(data, len);
-    }
+    decoder_ = std::make_shared<::arrow::bit_util::BitReader>(data, len);
     DecodeLengths();
   }