You have to be careful with blanket statements and definitions. Its supply is inflationary (until it stops being mineable, obviously) but it's price is (generally) deflationary (on average its price is going up). It's comparable to gold in some ways, e.g. very slightly inflationary supply, as its being mined, but generally considered to be a deflationary monetary system. Also, it depends on what time-scale you're looking at.