Test crowds have declined in recent years in India, South Africa, Sri Lanka, New Zealand and even Australia.
In contrast, fans have flocked to the one-day and Twenty20 formats.
"Test cricket is like a main course, and always will be - the other versions are like starters and desserts," Tendulkar, 41, told BBC Radio 5 live.
"Out of 10 cricketers, if you asked, I wouldn't be surprised if eight say that Test cricket is the top, then comes the rest."
Tendulkar, who retired from cricket last year, is the top run-scorer in Test history with 15,921 runs.
(BBC)