You could ask at the store where you bought it, whether it would shrink and what their advice would be, or contact the manufacturers.. but its probably made in somewhere in either China or Japan (!) or, you could wash it in cool water, even cold water, being that its 100% cotton, I doubt whether it will shrink. If it were me, I'd take the chance and do that.

Come to think of it, the store probably won't know either, although they may be able to give you the manufacturer's name.

if it's 100% cotton i'd wash it treat stains first. dry just until damp, then hang if you don't have a line, shower curtain rod or shower door works, that will reduce or eliminate shrinkage if it would occur at all.