diff --git a/README.md b/README.md
index 54dfa5e0..c80c8101 100644
--- a/README.md
+++ b/README.md
@@ -101,7 +101,7 @@ using QuantumToolbox
 N = 20 # cutoff of the Hilbert space dimension
 ω = 1.0 # frequency of the harmonic oscillator
 
-a = destroy(N) # annohilation operator
+a = destroy(N) # annihilation operator
 
 H = ω * a' * a
 ```
diff --git a/docs/src/index.md b/docs/src/index.md
index 531e606f..bc71957f 100644
--- a/docs/src/index.md
+++ b/docs/src/index.md
@@ -59,7 +59,7 @@ using QuantumToolbox
 N = 20 # cutoff of the Hilbert space dimension
 ω = 1.0 # frequency of the harmonic oscillator
 
-a = destroy(N) # annohilation operator
+a = destroy(N) # annihilation operator
 
 H = ω * a' * a
 ```